My concern was more about getting 3 or 4000lbs. of downforce on my hitch. My tractors run 6-7000 lbs with an attachment on the three point. If you get 6-7000 lbs of tractor up on a long lever between the back trailer axle and the hitch, its going to be pushing down pretty hard on the back of my truck.
i can't say i know anyone with a tilt equipment trailer, but i'd assume it works about like the thousands of tilt snowmobile trailers around here, though they are generally all single axles.
i believe that as you start loading the trailer the deck will start dropping. i don't think it could work any other way. you're never going to have any more than normal tongue load on the hitch. once you start to get the load past the axle group the springs and axles will start to equalize and the trailer will work toward its normal loaded stance. the highest tongue load will be at the final point where you park the tractor as you drive forward.