[skyking]

Great discussion
I have a much lighter trailer design in mind, and I am going so far as to design the wheel well area to accommodate either a pair of small 2200 pound axles or a single 5200.
My concern is the inherent bouncyness of ride with a single large tire/axle. I think a torsion with supplemental shock absorber will be a must with a big single. I have had torsions and the ride is great, but they were always tandems.
conventional spring single axles always 'launch' more than a set of tandems. More like a basketball
It is even more problematic when you try to cover a wide range of weight, as you are proposing. When light, even airing down the tires won't compensate for the stiffness of lightly loaded springs.