i hate using a truck because of the grooves in the bed. if i were to do it again, i would go buy some plywood. cut it to size and put the tank on it. then put a heavy blanket over the tank, maybe even two if your worried, strap it down and drive nice and easy.
i would also lay plywood down in the bed of the truck. i moved mine with the tailgate down 8 feet as well. and yes bend with your legs, get extra help, nothing and i mean nothing is worth tearing your back up.
I am thinking about other aspects as well, along the lines of how the freck are we gonna get my beast INTO the truck? Maybe a neighbor will pitch in a hand lol.