Starting on a project on the camper (Bigfoot 2500, 10.6) and as part of it, I needed to remove the bottom panels of the camper to see where the tanks are. I took some pics and stitched them together to give a rough idea of what the tanks and layout look like for anyone else that might want to know. The stitching isn't perfect, just working with the quick pics I could take.
Anyway, here are some thoughts...
1. The tanks are hung from the floor. This is a Bigfoot 2500 basement model. When the camper is sitting in the bed of the truck one would think the tanks would settle onto the bottom of the camper which would in turn be on the floor of the truck but that isn't really the case.
2. The tanks are actually suspended via the straps. The insulating foam (removed for pics) that was used is a low density foam and would compress easily with weight. This means, more than likely, your tanks are always being supported by the straps and not resting on the floor of your truck.
3. The straps, especially for the larger tank was insufficient. They also stretch it appears from years in service. The result is the tanks will bulge down where not supported thus leaving sections of the tank lower than the water outlet.
4. My fresh water tank and the way it was supported left ~20% of the water unusable due to first the straps sagging leaving the rear (where the hose connects) at a higher angle than the front of the tank. Also, the placement of the hose bib fitting means the tank will never be empty.
5. There is a LOT of unused tank volume available if one was to make their own tanks from aluminum or something. The tank height might be able to increase at least an 1" (maybe more if you weren't worried about having insulation between the tank and the fiberglass body). The front portion of the tank (L shape) could be widened maybe four more inches.
6. The grey tank (middle tank) could also be increased substantially. Additional strapping should be added and for some reason, the back strap actually goes over the sending unit wiring and fittings so it's compromised.
7. The black tank could also substantially be increased in size as well. Both in height and width.
For my current project, (and the amount of time I have) I'm just going to try to add more straps, address the budging and angles of the fresh tank so I get more usable capacity out of it.
For future projects, should I find myself with way more time, custom tanks could be made to increase the holding capacity for each of these by at least 15% if not 20%. I don't think I will ever get there myself but it certainly would be an interesting project.
1999 F350 Dually with 7.3 Diesel
2000 Bigfoot 10.6 Camper