Sorry to butt in on your conversation, guys, but I'm always dreaming of returning to AZ and check this forum sometimes....wish I could join you at the Cruiser Cruise!
If I can make a suggestion, I think BMAN is on the right track designing a custom trailer. I've put about 8 years and more money than I care to admit to fixing/modifying my M416 for offroad camping, and if I had to do it again, I would *definitely* build from scratch. There are too many downsides to the M416, from the length of the tongue to the dimensions of the tub, lack of tailgate, and axle mismatch. By the time you get to correcting all those things, you're already down the fabrication road, why not use the initial cash outlay to build something that suits your needs and matches your Land Cruiser? Just a thought.
The Canadian M101's are very nicely made, I had a chance to check one out at, of all places, the Military Vehicle Meet at Papago Park a few years back. Heavier duty than a US-spec M416, stronger components, but IMHO, the same limitations listed above. Sure, the idea that your trailer was designed to float is cool, but realistically, do you want the trailer to start doing so during a river crossing, swing around with the current and smash into the body (and with the short tongue, it *will*, my Cruiser used to have the dents to prove it)?
If you can pick one up cheap, then go with the M416/M101. But once the price starts to climb, and you balance out the cost of fabrication, you might be better off building. I paid $295 for my M416 eight years ago and if I had designed the trailer and built it from scratch, *once*, I'd be way under the current cost.
BTW, I'm probably still *persona non grata* in Glendale, I sanded, prepped AND painted my M416 project in the parking lot of my apartment building complex off of Thunderbird and 52nd! Not one of my finest moments....