I’ll try to be brief but this is a long story.
It was an original idea that turns out has many numerous executions. However, I did gain inspiration from the Karavan guy version, and he also has a large library of documented DIY’s on youtube.
I searched and combed the internet for the right size pre-formed PE tank to hang from L-track over the wheel well that would provide the slimmest profile and largest volume. Couldn’t find a good match for my current layout. I didn’t want the fabricated wheel well tank as they extend from the wheel well inward a good 3 inches which was more floor space than I was willing to give up as I use my TrackSprinter to haul my sportbike and dirtbike around.
So I decided to go undercarriage. Again, I couldn’t find a pre-formed tank that would provide the most ground clearance and volume. A large area under the drivers side is taken by two lithiums in a Hein tray. Thats when I decided to go PVC. I started with a plan for a 3vessel 6” diameter. I made custom end caps from flat PVC as the 6” industrial socket caps would not allow the 6” vessels to fit into the frame channels. When I went to go mock up the fitment, it all fell apart as only one of the vessels was going to fit the way I wanted. So I abandoned the plan rather than be unsatisfied.
Went with a 2vessel 8” diameter, one on each side of the undercarriage. 15gals calculated. I model tested the system with a small gatorade bottle and larger juice bottle and glued some tubing to simulate the flow and suction. It worked! So I set the plan in motion much like the Karavan version except with two vessels. This was many weeks in the making. Wasted a lot of time on the previous plan. And fabricating some ghetto stainless steel brackets and tabs cost me a few dulled drill bits, and took the most time for the finished project. Constructing the vessels was fairly simple. I used generic gas tank straps held up with rivnut/tabs to secure the vessels to the frame. I used rubber to insulate all installation contact points. I marked the nuts to track movement, and everything is solid. So far, so good. System works very well, and pleased with the results. Beach tested with the pup and have observed a dramatic decrease of sand accumulation in the van. Mission accomplished. Oh, and I riveted some thin pieces of aluminum together to make a catalytic heat shield. Boom.