thats a good question. I dont remember what the thread is, it may be 3/8 npt but I just have a 90 degree fitting to 1/4" hose barb.

Not sure I am going to put a gusset on the bottom not sure it needs it.
Right next to the down pipe of the cage is a tube that goes one side to the other side that the rear seat, seat belts, mount to. I think that will control any twisting that may happen.