I used to carry one of those cheap bolt-together trays (did it for a few years), but finally got tired of the janky construction, tendency to tilt to one side and general "sloppiness". My use is very similar to yours, carrying a 70QT or 100QT heavy cooler loaded with ice and venison/hog meat...
I did this twice, two different methods. First, the M416 shares shackles with the civilian Jeeps of the same era (CJ3s, I believe) and you can -or could, back when I did this- buy longer than stock shackles that will give you a bit of a lift. The aftermarket shackles are "H-shaped" vs. the stock...
I also ordered a custom axle with standard hubs that matched the pattern of my FJ62 and with the same width as the Cruiser's axle. I wanted standard 3,500 lb. trailer hubs that could be easily rebuilt anywhere in the US with parts from an auto parts store vs. the military ones, and the...
Axle with the right hubs should be fairly cheap, and they'll cut it to the exact width of the 80 series, that's what I did with mine. I only paid $125 for the axle but that was a long time ago.
It was very easy, I replaced the C-shaped shackles with regular H shackles (aftermarket CJ3 ones work) at the same time. I just used a winch to flip the trailer over in my front yard! :)
I sprung over mine and never had any issues with the trailer dumping, but I also ran bigger and wider tires on it (to match the Cruiser). I replaced the stock axle with an axle that matched the width of my FJ62, so I didn't have to carry extra spares.
I don't think your son's 50 quad will fit through the tailgate you'd be able to cut through it and still maintain strong integrity of the box.
I did an expedition trailer conversion on an M416 back in the late 90s early 2000s and loved it, towed that thing all over the country and it followed...
Many years ago I replaced the stock axle on an M416 with a custom axle with the exact width and hubs to match my FJ62, which made it a lot easier to tow on trails and eliminated the need for carrying different spares. I got this done at a trailer shop in Phoenix and it was around $200 or so. Ad...
Definitely started life as an M416, but it's been modified. The frame and tongue have been extended, the original fenders have been replaced, the original tail lights and mounts are gone, and it looks like someone cut off the welded tie downs used for the original canvas top. I can't tell for...
I don't have experience with these larger military trailers, but is there a way to lower the axle on the trailer itself? I'm wondering if the force of the weight of the trailer on the elevated hitch mount is what caused the issue, that's a lot of torque/leverage on the adapter itself being so...
This is one of my favorite builds on all of MUD, you did an awesome job thinking this out, planning it, and then executing. I built my own expedition trailer many years ago and it was much more haphazard than yours, wish I could do it again! :)
I've carried NATO cans on their sides (mounted to my trailer) for years without any issues or leaks. No experience with Scepter cans mounted ot the sides, though.