No that I get, thanks for elaborating. I didn't think about sitting on the tires and no safety stops, which are needed just as they are for a 4 post drive on lift. I was looking at it from the frame of mind I was pondering regarding my frame fixture, and didn't consider that it's now setting on rolling wheels. My main focus was difficulty in getting outboard enough for stability, which was accomplished by him getting under the tires. Extreme caution is required when working beneath equipment.
And regarding balance on a frame lift, it would need careful confirmation, but I think mine would balance quite nicely with the loader in place, but be tail heavy without, and of course nothing on the 3 point. But I would certainly verify before going to that much trouble to build, much less getting under it in the air.