Ok, I'm going to go ahead and be the one to say it - really bad idea.
Nothing you can pull will keep you any safer from bears dogs and rain than a tent. If a bear wants your food, it will get your food. Dogs aren't a problem at night. Tents are waterproof if you get a half-decent one.
But, while you are riding, you will be miserable with the extra weight. Sure you can pull 60 pounds of trailer but don't you need all that other stuff too - like a sleeping bag, cooking gear, clothes, toiletries, etc? SO, then it's what, 100 pounds? More? Remember, it has to be durable enough to take miles and miles of rough road.
And then what, it's like, at least 6 feet long, where are you going to park it? What if you have to take a car ride, or take it upstairs in a hotel? Can you carry it up stairs? Fit it in an elevator? take it on a train or plane?
OK, and then, you are building it yourself, right? How does it attach to your bike? How does it affect your bike's handling? Is it safe to tow down hill, or does it want to come around and pass you , remember it weighs 60-100 pounds, does it need it's own brakes? How willl you know these things without finding out the hard way?
When it's parked, is it on it's wheels and then with braces in front/back? Does it have to be parked on a level surface? how do you get in/out of it, and is that door water proof? bug proof? Does it collect condensation overnight and then retain that moisture all day? Is it broiling hot at night? Does it need a window? Is your other stuff packed inside it during the day and then you get to put it where at night?
What problem are you trying to solve, and what new problems do you introduce.