Thanks for the comments.
Yeah I am still a bit undecided on what is going to be put on the back. I am leaning towards a flat bed with stake sides. As it would let me haul around my gooseneck trailer and serve as a regular pickup bed when needed. Though I am still a bit tempted to put the service bed back on, as it is in very good shape and would let me haul a lot of gear.
Another idea would be to go with the flat bed with the removable stake sides and also make a frame that can hold my welder and tool boxes. So when I need the welder and tool boxes, I can just pop it on the trailer and bolt it down. Yet when I just want the flat bed, it would be easy to just pull off the tool setup, giving me access to a complete bed.
Ideas, ideas