Trailer with fixed coupler so it doesn't pivot

I've never seen one like that. About all you can do if you don't have a back-up camera is to mark the corners of the trailer with poles/pipe that sticks up high enough for you to see when backing and you just watch the poles/pipes. I've seen little fiberglass poles with magnetic mounts that could be used for this purpose. I used to have to back a log splitter that would completely jackknife before you could see what was happening. Not fun.