Cordless drill - I use it with to make dirt holes, screw in supports and anything else that needs it, twisting heavy wire and...I carry two batteries and one is always being charged in my side by side.
Combo Tool - Hammer, digger and hole maker. When I have to carry gear it its really nice having one tool that does it all. I have tools that do the job better for each job, but when you need to move through thickets carrying a lot of gear less is better.
Shifter - I not only use it for shifting, but if I find dry dirt, which is hard to do down here sometimes, I will pre-shift it into a 5 gallon bucket, saving time on the line.
Other items I use and couldn't live without -
Buckets with lids - Like I said if I find "perfect" dirt I load up and carry it with me. Its makes life easy.
Small block of 2x4 - In soft dirt or mud it makes setting a trap a whole lot easier and safer. Also, you can get the levers level with or lower than the base plate which makes the trap easier to set. Beginner trappers who go out with me all carry a block of 2x4.
Pirogue - Even if you don't ride in it, you can load it down and pull it behind you. When you are in knee deep swamp wading it makes life easier. I can load it down and it will float in an 1" of water. You have a bunch of otters and beavers? Just float them out!
Honda Pioneer 700 - The Goldilocks of utility vehicles. Its small enough to go down four wheeler trails, but big enough to carry a ton of gear. You can pull a small trailer with it if needed. Not having to climb on and off a four wheeler is nice when you have old combat wounds and injuries. It also has power steering, two places to plug in battery chargers, a roof, windshield, winch and a gun rack that is mounted inside the roof keeping a shotgun and rifle secure but out of the way. It is really quiet which is a bonus.
1st Aid Kit - In my Honda I carry a serious 1st Aid kit. Can't tell you how many times I have cleaned a wound, patched myself up continued trapping. It helps keep infections down from cuts and scrapes, keeps you from bleeding all over your gear, clothing, and vehicle. It might save your life or someone else's, and fts in the glove box.