Years back we some times camped in areas where one side of the trailer had to be ramped up maybe 6"-10" and the other sitting on the ground. Blocks of any kind behind the tires wouldn't stay in place so the 5er would roll of the ramp.
I fixed that with adjustable chocks between the tires on both sides. Left the wheel chocks in the trailer shed.
I bumped the 5er hitch real hard one time with the wife inside getting things ready to go home. One side of the trailer was up on blocks enough that the same side of the truck had to be blocked also. It was muddy. The trucks rear tires slipped off the ramp just as the pin started in the hitch. The trailer spun around about 2'. The wife flew out the door squackin'. Thats when she decided I was spend some bucks on a pair of adjustable tire chocks. That was in the early '90s and I forget the brand name.
I still use them with or with out the trailer being ramped.