I can't wait to see it!! May need a couple of more steps out the door too!
I don't know if you would have any of this stuff laying around in your area....But I got a hold of a sign for traffic control or road construction. The "left lane closed until such and such date" type of sign. The axles under some of those are beefy!!! It's one of the bigger hubs I've seen on a small trailer. They also have pretty heavy duty hydraulic type brakes. They have to suport the weight of the mast, sign,hydraulics, up to 16 or 18 batteries. Usually they end up in the scrap yard after a hit or blow over.. It cost too much to repair them. But make great heavy duty trailers or axles. The older signs, the new ones have LED's and one or two batteries. They aren't built as heavy. But I see them sitting around in back lots of old construction companies too. Picked for parts.
The hydraulic brakes system could even be used. Just throwing an idea in case you happen across someone with them just sitting around or need an idea to go bigger, not sure what type of strength the camper axles or hubs would have banging around offroad with that size tire.. I was told to "please get it out of here" when I asked for mine. haha We made trailer out of it and you can't overload it. I had 2 ton or more of gravel in it!!! The tires looked like they were ready to pop...but didn't hurt the trailer. The springs could probably be used too.I know that's nothing for bigger trailers but this is about 5ft by 11ft. I've bounced the rims Hard off of rock and trees, just give it gas and pop it around it, can't hurt it. They are 5 lug and think it even fits a common truck rim size I'd have to measure. I haven't broken a hub yet.
Anyhow just throwing ideas, I love projects like this and miss doing stuff like this!!!! I have to look forward to your posts to see what's next!!!

Wish you were one of my neighbors!! It gets pretty boring here!