Im sorry to come into your post but could you tell me what is inflatable bellows? I would like to have my van heightened to be able to get up some hills without scraping the back end or come to that the front.
I live in a hilly area, so scraping the tail is quite common.
If you raise the suspension above what it was designed for, you will get problems with the drivetrain: the joints won't be running straight.
If you fit bigger wheels, you raise the ride height by only about an inch: not enough to significantly reduce the chances of tail scrapes.
But before making any changes, it might be better to diagnose the problem.
Is it just that your suspension is lower than it's meant to be? Perhaps the springs have weakened and are sagging, or perhaps you are overloading the vehicle.
Either of these is best cured by fixing the problem rather than hiding it with air suspension.
There are two sorts of air springs you can add: the cheaper sort replace the rubber bump stops and are inflated by a hose. They just help the existing springs take the weight. They cost a few hundred pounds.
The better solution is to replace the load-bearng springs with ones that only hold the axle in place, and fit proper air springs to carry all the weight. This gives a far better ride and is more controllable (you can let them down for levelling, pump them up for steep ramps).
Normally they have their own air tank and pump, and work automatically, levelling the vehicle whatever the load. You see them on the back of tipper lorries. A good solution, but they cost a few thousand pounds as a retrofit. Unless your van is fairly new, probably not economic.
One other thing you could consider is a strong tail. My motorhome has a towbar (though I never use it to tow) which has heavy nylon rollers at the ends, so when the tail strikes, the rollers take the strain and prevent the bodywork hitting.
There's not usually enough overhang at the front to be a problem. Does yours sit very low, or does it have a big front overhang?
