Here is one of my ATVs that I use on my traplines. The box on the back has 2 compartments and doors on both ends. One section holds small hand tools, wire, flagging tape, and other small items. The other end holds my setters, tomahawk, anchor driver, and what ever else I need to put in there.
I was thinking of mounting a couple of brackets on the back side and mounting the gun holders to the bracket.