Installing large holding tanks
Im looking for any info / ideas and advise when it comes to installing larger holding tanks in my '77 Argosy 26 obviously rear bath. Most of our Tx State Park camping doesn't have sewage and although the tote tank isn't much of a hassle I would rather have tanks that can support my family of three for 2,3 maybe 4 days but I doubt it, we like to use water.
So heres what Im thinking. The black tank isn't really the problem it the grey which is only about 14 gallons I think. It seem logical to get rid of the above floor black tank and make the existing grey tank the new black tank. Then install a new 40 to 50 gallon grey tank just behind the rear axle and maybe the same size potable water tank in front, between the two axles.
I have some rot in the rear subfloor that needs to go, so I will pull out the bath and the beds and remove the last to sheets of plywood subfloor. With the belly pan removed this will give me complete access to the frame. The potable water tank will happen at a later time. I am familiar with the frame structure from replacing the front subfloor and I can see where the cross members are located based on the floor bolts. I will most likely not tow very far with a full grey tank but the frame should be reinforced assuming I do. I can tell you this about the frame. The cross members are on 4' centers with two 3/4" x 2" aluminum purlins between and parallel to the main frame rail. So I potentially have have a lot of room between cross members. I also know tanks of this size will be below the frame rails so a new belly pan will have to be made.
Im looking for any advise, good or bad and pictures of installs particularly in regards to supporting the tanks and reinforcing the frame, to help me work this out before I tear into it. I want to have a clear game plan with the parts on hand and hopefully avoid any surprises. Thanks !