Tim,
I sounds like you're putting a lot of effort into developing a new reverse tow trailer. It looks very nice.
But not being a guy to sit still without "offering" his 2 pence of wisdom, wisdom is being used here very figuratively I might add, I've got a thought that could make your efforts more attractive.
I've looked at motorcycle trailers for years and now with auto loading pickup box screw drive loaders, there's a new wave of self lowering trailers that allow you to ride on without ramps. It's the without ramps that got my attention.
In most cases they use independent stub axles on torsion levers, one for each side. The axle cannot connect from side to opposite side, see the video.
The Baxley trailer is quite cool in design. Here are a couple videos of them.
Baxley SB001 Trailer Baxley SB001 Lowering Motorcycle Ride On Trailer The two above videos show the Baxley with a side to side connecting axle with torsion leading link side suspension.
Also notice in the first video that they have preset straps that they snap to the surround tilting frame so when it's lowered it pulls the bike forward right at the end of the outside tilt frame being latched. This feature could also be used with the M3W. You could have a web harness that you drive over with the front wheels while backing onto the trailer. After driving onto the two outside M3W front tire supports, these would be special for the M3W, you would take a strap and attach it to the raised outer tilt frame. Then when lowered it would snug M3W into place. Maybe then just one quick tie down for the rear wheel up front and you're loaded.
Easy peasy...
I used "tilt lowering motorcycle ride on trailer" for my search words on YouTube. There are a ton of videos about non-ramp trailers and as long as you're going to the trouble to make a trailer from scratch, or a boat trailer company, why not make this a very cool trailer without much in the line of work required to load or unload.
Removing the ramps would be a BIG plus in design.
Sorry for always adding my thoughts here and there, hope they help you out.
Good luck with your venture with the trailer design.