Going back 20 - 30 years, all TCs were wooden framed I believe - at least most of them. My jacks were lagged into the wood on the corners. Occasionally the lags would come loose. When TCs develope a leak, it causes wood frames to rot. Sometimes that hidden rot occurres at the corners, then the lags pull out and down comes the camper.
I always stored my TC on four drums or a stack of pallets. It was very cheap and easy insurance if the jacks failed, a strong wind came up, the ground softened due to rains or other unexpected problems occured. After all, it isn't a problem until it is a problem. Do you have a plan for getting you TC back up and onto the truck if the jacks fail and it falls over?
Bill