Got both water tanks in. I measured actual volume to be 26/40 so 66gal. Simply used 2x2 screwed down with expanding foam for cushion. Use foam for lots to keep things tight through vibrations, worked excellent in the bus. Also used some bubble wrap at the base.
Adjusted two of the water level meters, med to high spot on small tank and added a new high level into the other tank for fairly accurate readings.
The pump is adjustable and easy access. Water fill is in as are both air vent tubes. Outdoor shower fixture (black plastic as with everything else) is in but none of the pressured water is installed yet.
Fill was placed as high as is comfortable to fill and the shower is out of kids reach by themselves but at a comfortable hight for usage.
Had to change out water intake so it’ll now fill at the base from the larger tank to the smaller one. Also water drain spot for both tanks, the T coming off.