Great advice everyone, thankyou. As I mentioned, the axles are very easily moved. There is a series of bolt holes along each side of the trailer frame, and the axles and springs are all one unit. It will be as simple as testing the balance and tongue weight, jacking up each side (at the same time) and moving the axle to the next position, drop the jacks and test. Repeat.

The wheels are a bit splayed out. I questioned it also, when I bought it, but I jumped up and down on the trailer and with some weight they lean back in. I think it's just because the trailer is unloaded.

Still not sure whether to go rollers or build some carpeted bunks in a v-shape. The beam supports are a good idea, but maybe not for me.

I'm about to pick up some 3/16 wall 1.5 in square tube to weld two cross beams on top of the frame, about 8.5ft each. I'll also extend the draw bar a few feet - not sure how much by.... maybe attach a 2x4 board on the draw bar, extending beyond the hitch, and back the car up at the most extreme angle I can ever imagine turning (right angles I guess) and move the 2x4 until it looks like a safe clearance. Then measure and replace with metal.