Your idea has merit but I don't think a copper sleeve will be sufficient. Copper might be too soft and bend or break on you with a large beaver or otter. I think I would use a steel sleeve instead. If the water is deep enough, your trap doesn't have to go past the joint. Might consider using wire or cable to get the added length your looking for.

Good job on the beavers yesterday! I use 10' 1/2" rebar but only take 4-5 with me as I too trap from a boat. The rest of my traps are conibears or old fashioned cable and sash weights with MB750's.

What your preferred drowning rod length? Rookie question. Trapping a new spot. It's a bit of a reach for the 8' fiberglass rods to reach the deep water. Considering adding an extension to them. I'm thinking about using 1/2" copper pipe as a sleeve and bolting it onto to the bottoms. Not sure what final length I want.

I'll take that into consideration. I mentioned copper cause I know the the ID is 1/2". Not sure about steel. However the 2 - 4' that I add, most of that will be in the mud. I don't think it will matter. Guess I will find out. They are strong critters. Found that out already. Which length do you prefer? Can't use cable. I need the to keep the weight down. The less weight, the better. Otherwise the boat won't get on plane if your loaded up w/ beavers. Found that out already too. 7 total yesterday. 60 lb, 57lb, and 47lb. Long ride back to the ramp.

With all the helpers along you could have them skinning and leave the carcasses for the critters to eat-problem solved.