Steve Walker explained on 14/07/2018 :
Almost any caravan which turns over onto its side, will lift the rear of
the tow car off the road.

Not sure that'd have been true of the 60s and 70s cheap end of the market -
the roofs would bend as you tried to scrub them clean at the beginning of the
season!

True, but we are discussing a caravan going on its side. Its chassis
laid on its side is what takes the load and does the lifting of the tow
car.