You're limited to the tongue weight. My 2017 thor 23u says 500 lbs. Tow weight is 7500 lbs. Usually 10% of tow weight is normal but a lot of these RV's have extensions added to the back.
FWIW I use a ultimate mx hitch rack, holds the bike by the foot pegs. Goes on tight, doesnt wiggle like those with nylon tie down straps, doesn't come off. Safe and easy no tip over hazard like on a ramp style. Just jack it up.
I've used it many years. Carries my ktm 500 (260 lbs) ktm 625sxc (340 lbs) and my xr650r (308 lbs . Personal favorite)like not even there. All my bikes are dual sport, street legal. I suggest you get a dual sport of which there's many varieties. Been a lot of places, seen a lotnof country. Also the rack is useful if you gotta fix a flat tire.