I'm looking at a sales brochure for the 1973 Amerigo
and it indicates that overall height is exactly 7' 0". The Amerigo design is a much lower profile than most so is the problem that it is lower than it was when new or do you just want more ground clearance, or both?
The sales sheet mentions "Torsion Bar suspension", "Rubber mounted torsion bar suspension" and "an independent rubber mounted suspension system, identical to the ones used on the largest and most expensive travel trailers". With those descriptions, as I could only guess what's there, you might take a look and tell us what you find so we can offer more suggestions.
But to repeat, the stock Amerigo rides much lower than most other FGRV's, the kick-up in the front frame sorta attests to that issue.