A couple of things to keep in mind...
They are designed to lift light weight pop-up style campers in the low weight arena; even with two together, they aren't designed to lift several tons (my 210WBS came in at 3 tons loaded for travel) and could collapse if overloaded and could do it when you least expect it. Keep fingers out of any area that could be crushed if a catastrophic failure happens. You are exceeding their design limits so there is no inherent liability that the company would be under if you lose a finger or two.
The other issue is the design of the base. I saw one on a pop-up and even with that light weight, on soft ground, the unit easily sank an inch into the ground overnight. The owner finally had to put the tire on a board and then use the lift device in order to keep the unit level. He saw my "lego blocks" and told me he was going to change to that system; if he had to carry a board for support, he might as well just carry a light weight bag of the blocks.
Do what you like; just be aware that you are using a device for a purpose for which they weren't designed. For my money, the lego blocks are just as easy to use (easier, they don't require a wrench), don't sink in the ground and are virtually indestructable...