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I won a clone of the Bob trailer. The one wheel trailers are easy to pull and don't wear your legs out. However they can be difficult to load without flipping your bike. I'm using a folding bike with twenty inch wheels and if I angle the bike just right I can put one side of the trailer on the concrete while I strap down my groceries. But when I use my beach cruiser bike, even with the double type of kickstand that lifts your front wheel a bit it is still difficult to load the trailer without flipping the bike. For short trips around town without being challenged by hills I feel that two wheel trailers are better. For longer trips the one wheel units will save you a lot of sweat.
If the sidewalls on the trailer are taller than the wheel then you could even carry a 4x8 piece of plywood laying flat on that trailer. It is versatile and well thought out. One could also make that trailer in wood and avoid the harbor freight expense.
A bicycle built for two can also be used as a pack mule. But I do sort of think that some sort of large basket on the back would be a good way to go as the types of things you might want to haul could be expanded. For example suppose you had a weeks worth of laundry to lug with you to the local laundromat . Those bins couldn't haul it although the weight of the laundry is fairly low, the bulk is the issue. But you did a clean job and built a useful device for your particular needs.
There is a risk in any shelter under a tree if lightning is taking place and with rain there is usually lightning. Modern carbon fiber fishing rods are also prone to drawing lightening to the user. In my part of the US shelters are far safer if they are well off of the ground. Poisonous snakes tend to seek out dry spots when it rains and warm spots when it is cold. More than a few people have woken up with a coiled rattlesnake of their chest or in their groin or armpit. And we also have wild hogs that will tend to attack people on the ground as well. To me the best single shelter is a jungle hammock. It keeps you out of rain, mosquitoes, snakes and wild pigs and can easily and quickly be strung up and ready to use.
I would find the need for a toilet to be a basic requirement.