Great idea. As long as the tape holds it will work. If the tape give up in water, just punch holes along the edges of your jug and the cut out piece and "thread" it with zip ties along one edge so that it can still hinge open, then put a couple of holes along the opposite edge and use a wire closure that you can easily untwist to open when you have crawfish in it. Also, punch some small holes in the body of the trap so that it won't have a tendancy to trap air and float.
When I was young we used to run crawfish traps and catch sacks and sacks of crawfish for eating. The last time I went crawfishing on that scale, I came out of the swamp with a leach on what you might call a "sensitve" area and decided that when I want to have a crawfish boil, I'll just buy my mudbugs.