Very neat engineering. I daydream about adapting a small boat trailer to carry a Spyder. All-up weight under 1800 pounds, I could see an aluminum T with a front crossmember added to carry the deck.
To make it kneel for loading, how about this: mount the axle and suspension through a C channel running upside-down under each side. Leaf springs are held at each end with a piece of box steel that fits in the channels. The steel has rollers ahead and behind the trunions/spring bushings. There’s a cable attached to the axle that runs forward to a winch, and backwards to a pulley, then forward to the same winch. You pull four bolts, crank the handle one way, the axle rolls forward uuntil the tail sits down. Lock it there, winch the car on, then unlock and crank the handle the opposite way until the backside lifts and the holes line up and you put the lock bolts back in.