I have an 87 YJ, 4.2L, AX15, 8.5 inches of lift and 33's, My rig trail ready is at 3750 according to the truck scale at the local papermill.
I dont see where you are getting close to 9000lbs, even with the trailer and people.
A buddy of mine pulls a bogger full sized chevy on a twin axle car trailer, with a full tool box, torches and spare parts out the wahzoo, with a chevy avalanche, and he does fine.
I would think a tahoe, or expedition would be able to handle a YJ on a car trailer without any problems. Depending on the placement of the YJ on the trailer, you might need a weight distribution hitch, but the tow vehicle should be able to handle that.
A nice big 1 ton dualie would be nice to have, but not practical....Just my 2 cents.