I have also daydreamed about fining and using tractor trailer fold down type legs but my idea was to get rid of the fold down part and mount one double to the front bumper/frame and one double to the back? Still picturing the look of it finished and although very doable and would work flawless with a drill. I don't know that I like the look exposed on the front bumper and I have plans for bumper extension,porch, tow hitch type thing that I could still make them work with but not really liking that picture either?
I think rjnyes idea would work and you could put 4x4 or 4x6" wood blocks in between the spring and frame to stiffen thing and put the jack stands under the axles cause the shorter the jack stand is the more they will be.
Don't forget you need something between the feet of the stands and or the jack to keep them from sinking into the dirt,rock, asphalt and even concrete because you don't know the thickness or quality of the concrete.
I have also thought of an idea to mount air powered bottle permanently underside in there respective position but fold up and pin in place when stowed and fold down and pin in place for use and can extra blocking/base plate material to keep them from stretching out all the way to hit solid ground,blocking or(you get the idea) the only draw back to that idea is that just like any bottle jack they need pressure on them to retract fully so do I lay under the bus and push them up to stow them or Carrie enough blocking to limit the amount of ram travel and lay under the bus to screw and unscrew them off of there blocking?
Just trying to share ideas?