Aaron,
When I saw the way the back of your Tucker is secured to the trailer it brought back a memory, and a suggestion for you...
Several years ago I trailered a vintage muscle car to a shop in Idaho to have it professionally restored. The shop owner complimented me on the way I had secured the vehicle to the trailer (heavy nylon tie-down straps attached to suspension components
below the springs).
I was somewhat surprised by his comment and he related that a few years earlier another customer had trailered a very rare Pontiac GTO to him for restoration, and had chained the car to the trailer
above the springs. The fellow had driven a long distance and when the trailer encountered a significant bump in the road, the car's suspension would naturally compress with the bump and create a bit of slack with the chains. When the suspension then rebounded, the travel was abruptly limited by the chains. The result from that suspension action over the trip was some wrinkled body panels which cost beaucoup bucks to fix.
My snowcat buddy, among his talents, is a genius at securing stuff to trailers. Not just the general concept, but he knows lots of tricks, different knots, etc. Through osmosis (and embarrassment) I'm learning from him. My understanding of the "proper" way to secure a snowcat to a trailer is to use the tie downs in a "X" pattern, both front and rear, and attach the tie downs below the springs, to either the axle housings or the carriers. (On our Thundercat project we welded shackle clevis mounts to each of the four carriers for that specific purpose.)
Last winter I had the opportunity to go on a Tucker demo-ride, and naturally took a slew of photos. Apparently Tucker agrees with that tie down methodology. Here's a photo of the way they secure a machine to the trailer.
We haven't used the clevis mounts yet, but prior to that we used heavy nylon axle straps (they have rings at both ends) to go around the Tucker's axles just outboard of the spring perches. The ratting straps we use have hooks at both ends; one end attaches to the trailer, the other end's hook goes through the rings on the axle straps.