Sometimes getting the pump below the tank is not possible (unless you mount it on the rear end, not). Get it as low as you can preferably on the inner frame rail and getting it as close to the tank as possible is just as important.
Have it currently mounted on the right rear lower inside frame rail where the front of the leaf spring is located. Then hung the mufflers and there is only about 1/4" clearance. Kinda worried about the heat?