JTs or a similar product work great for lateral and up and down movement.
I've used a aluminum bipod pin stabilize since our first 5th wheel trailer in 1990. Didn't take but one trip till the brain kicked in and figured out it can only stop lateral movement at the front of the trailer.
Bought a BAL telescoping stabilizer for the rear of the trailer which stops lateral moves back there ....and adjustable chocks between the tires that eliminated fore and aft movement for a rock solid trailer.
I've used this method on three different 5th wheel trailers.