Something you may want to consider is adding some type of flags to your trailer. I towed a utility trailer (48" inside the wheels) behind my full size Chevy, if I had anything in the truck bed I could not see the trailer. I could not see the trailer in the truck side mirrors which made it really hard to back up, if you could see the trailer it was already turning which was too late (because it is so short).
For my trailer I made some removable markers that angled away from the trailer, I put them at the very back off the light bracket. Now I can see the trailer in the mirrors and I know exactly where the back of the trailer is.
Try to picture markers similar to what you see on the edges of truck mounted snow plow blades. I'll try to take a picture tomorrow.