Launching with your front deploy-able wheel is probably good but hauling out by hand might be tough. Having a really long line so you can hook up to the truck or maybe a winch mounted on the trailer to pull them up an incline.
I suspect the 13" tires will hold up just fine but you might want to either go larger or do a frame lift to give better clearance if you are going to take it over rough areas, so the frame doesn't bottom out.
I don't know if you could retrofit it but the cover from an enclosed snowmobile trailer would address the road debris damage better than the brush hanging off the back of the truck. Plus out of sight is better for security.
