"There's crawl space under my floor."
Then...
When weather permits crawl in and use basic/inexpenisve items to support the floor under your TT.
You would need to lift the joists (scissor jack form your car?) maybe half an inch, or so, and then block/support them with cinder blocks/and perhaps suitable non-compliant shims allowing gravity do it's job once the joists are lowered.
Hate crawl spaces myself, but once done (depending on the lower/ground surface) the remedy should last years, if not decades.
I used to place my TT's in closets (including unused Murphy bed closets) in old rental units due to to the added bracing/structure those specific areas afforded.
Curent TT is also in a closet (along with all the electronics), but for other reasons.
I now use specialty shelving, upturned brass spikes, et cetera, however my floor is quite stable (aside from the occasional earthquake and/or Air Force afterburner flyovers/drills).
A stable floor is the main goal, if it can be accomplished within reason/budget.
DeKay
