After installing a new axle
I gained 2" more inches of space above the axle. Perfect spot for a 2nd fresh water tank. There are hundreds of tank available, but most are weeks out. I lucked out and found a perfect fit with this in stock 39 gallon tank
The main location where the extra tank will benefit us, is at our hunting property in upper Michigan. I don't mind running a little excess grey water into the woods, or a shallow hole in the ground.
Since the new axle increased my weight capacity by 900lbs, I've easily got enough to carry the extra weight and it will be carried directly by the frame reinforcement I built for the new axle. The camper frame or body won't see the extra weight at all.
It was actually a tighter fit than I thought, but I got it to go. It would have been easier if I had planned a tank with the axle upgrade, but I got lucky and didn't have to drop the axle to get the tank in.
I welded up some angle iron brackets to support the tank and installed blocking (to the floor) on the sides to keep it from moving around.