As we left the hire depot like a motorised snail, my head was full of phrases about liability, "damage deductibles" and causes of collision for which we were definitely not insured - such as reversing, or striking anything sticking out of the ground. We did, indeed, have one small accident, when a rock knocked our porch steps sideways. It does not take a company lawyer to argue that a rock is something that sticks out of the ground, and we there and then imagined waving goodbye to our large deposit.
At the campsite that night someone tried to bash the steps back into place with an axe, but that was done more to be obliging than with any real hope of success. So we went to a garage. Might it just be possible to make things pretty much as good as new? "No problem. Cost you 10 dollars," said the mechanic, as he got out his pick-up truck, attached a tow rope to our steps and revved forwards. Crunch. Our steps were fine again, but he had driven straight over an aluminium ladder. Nick, our three-year- old, thought it hilarious. Still, our problem was sorted out, and when we took the RV back it had barely a paint fleck out of place.
This, then, was truly an idiot-proof successor to the covered wagon. In it we travelled without wilting through the heat of the Mojave desert, and slept in comfort when the snow flurries came down from the Sierra Nevada. But we started modestly enough from San Francisco with a drive down Highway One to Big Sur, where we camped among the redwoods.
The sea mist stayed offshore and the sun shone. We walked in the age- old forests, played in the silver sands of Pfeiffer beach, swam in the Big Sur river and took things easy - when Eva, our (almost) two-year-old, allowed.
In American terms, Big Sur is not far from cities, and this part of the state is still Joe Sixpack country, where having enough beer is as important as being out in the woods, and the trip to the camp's general store for resupply counts as a walk on the wild side. Two days' travelling inland took us somewhere far more remote.
For those reared on Sixties cowboy serials, Lone Pine is a place of pilgrimage. Half-a-mile west of the Bonanza Saloon are the rocks like upended doughnuts where the Lone Ranger and Tonto were ambushed by bandits every week at 5.30pm. The place makes a decent living off fading black-and-white memories, but it is also a trading-post for people seeking a more modern wilderness dream. A few miles further west is the start of the path that leads to the 14,000ft peak of Mount Whitney, the highest point in North America, outside Alaska. The mountains drop almost sheer in great granite slabs to the valley floor, and desert scrub and deep blue skies stretch hundreds of miles north to Mono Lake. We had looked for a week to find a landscape that was not dwarfed by our camper van. At last we had found one. From the Whitney Portal campsite we were in an ideal position to explore it.
With judicious use of cajoling and cookies, Nick was persuaded to make the climb of 1,000ft or so to Lone Pine Lake. Fortunately, something of what I had said about the Lone Ranger had sunk in. "Is this where the man will jump out from behind the rock?" he asked impatiently as we passed the umpteenth likely spot. The lake was a deep turquoise, the surrounding slopes white rock dotted with old pines, and at one side there were still drifts of snow. In the pure air of the mountains and with no one but the birds for company, we had one of the world's best ever picnics.
By this time, the RV had taken on the character of a real family home. We could cook when the children needed food, time our longer journeys for when they slept (strapped in robust car seats, which we also hired), and play their story tapes in stereo. Quite unlike their parents, our children have always been near obsessive about things and people being in the right place. Nick and Eva quickly established which cupboards held which toys, where they sat to eat and which were their beds. Given this secure base, they felt happy to explore, and most of our time was spent outside the van. For little Eva, a limitless supply of small rocks, and streams to throw them in, gave life all the purpose she needed. For young Nick, helping with the everyday routine of gathering wood, and the tameness of the campsite rodents and birds, were bliss.
After five days near Lone Pine, we set off to see Yosemite and the giant sequoia forests on the mountains' western flank. As the eagle flies, the distance is barely 40 miles. But road crossings hereabouts are hundreds of miles apart and reaching Yosemite over the northerly Tioga pass took another two days of unhurried travel.
It is a characteristic of all tourism, but perhaps particularly of the Californian kind, that the second most spectacular example of anything is not good enough. The result is that the Yosemite Valley is a teeming honeypot into which 4 million people crowd each year. It is indeed an awesome place. Yet 100 miles south, in the Kings Canyon National Park, the cliffs and waterfalls are scarcely less spectacular and can be enjoyed in relative calm. Whereas Yosemite's tent lodges and camps are booked solid months in advance, the King's Canyon site of Cedar Grove had spaces. So we spent one frustrating day in Yosemite, and a peaceful week among the lakes, azalea groves and lily meadows of Kings Canyon.
Such tranquillity was a far cry from our first few days with the RV - which had seemed like holiday hell on wheels. Initially we had found nowhere to stay except specialised mobile home sites. These allow you to hook up directly to fresh water and electricity. But they are soulless, oversized car parks.
"Hey, you can't do that!" a nosy neighbour told us. "Do what?" I asked innocently. "Hang your washing between the orange trees," she replied. No doubt ours was the only vehicle on the estate without a tumble dryer. But once in the hills it proved no problem to find unregimented sites that were quiet, but still spacious enough to take our lumbering vehicle.
It is difficult to know what exactly the children made of our experience. For Eva, it was probably just the joy of the moment. But Nick still talks fondly of his bedroom at the back of "Arvie", and of waking in the morning and drawing the curtain back to look at the trees. When we returned to San Francisco, both he and Eva seemed startled by the crowds and the strange dress and behaviour of the people who live on the city's streets. It seemed in many ways a wilder place - a human zoo - than any we had encountered in three weeks in the woods.
Plenty of US specialist tour operators offer recreational vehicle rental as part of a package holiday. If you prefer to organise things independently, you could call one of the following agencies: Cruise America 0990 143 607; Hemmingways 01737 842735; Motorhome Holidays 01424 814100; Pelican Car Hire and Motorhomes 01625 586666; or USA Tailor Made Holidays 01732 367711.