I've often pontificated about this problem on Towables and MHs.
Since most Towables seem to have the same standard four wheel 2 axle spacing why don't they install a, not bare, steel which would rot in short order up north but, as substantial steel alloy can to shield the RVs from road objects and blowouts.
Many are maimed or killed every years from blowouts on MHs. 250.00 to 350.00 max for such protection on a Towable and perhaps another200.00 or a Motorhome.
For MH's at least they could install the safety devices that are like an inner tire, on the steer axle. They are hard to find now but if the factory installed them they would soon be more available.
Go ahead and put the steel cans under your rv. The best idea yet. Make them heavy enough they won't rust through. Maybe a metal dealer can steer you to an alloy that is rust resistant.