If I were you and you absolutely insist on keeping this thing on wheels I would go the liner route. That would solve the issue of a seam bursting. If you do go epoxy that's where I see you having major issues so I would seriously encase that thing in multiple layers of fiberglass first to make it as rigid as possible. No matter how much support you go with it is still wood and without it being fully supported on the bottom it is going to flex and epoxy will Crack and you will have leaks over time. Other than that issue (which is a big one!) The build looks fantastically over built which I love