I would keep it. You are not going to use it that often and when you do it will be to drain off the grey tank. Yes, 42 plus gallons of water is heavy but you are only dragging that from the TT to the TV hitch and you can always drain off a smaller amount and make more than one trip.
Our tote goes in the back of the truck but I have seen people attach them to the back bumpers and ladders of TTs and 5ers. I also bought a tote smaller (30 gal) than our grey tank but to me, it not an issue since we only need to dump the grey tank once in the course of 3-4 day stay.
