This will be a Moab trails only setup I built a rear deck cover for our JKU, out of 1/2" plywood. I was thinking of attaching a Rotopax mount to the plywood and either using a 4gal Rotopax, OR a 2gal fuel and 2 gal water Pax.

Here's the mount






Have it laying flat, right behind the rear seat







I will be removing the soft top while in Moab, and will only fill it w fuel once I'm there. When we leave Moab to head home (stl) I will have it empty. Any thoughts

 

Seems fine to me, I think if you only use them when your tops off you'll be fine