Nice yeah if your at the same thickness and you have 100% incapsulated the wood I would agree you are all set. Realistically the only reason they fail is water intrusion, if you really take your time a seal it it will last a life time.
For the tank I’m planning on no foam. The aluminum ones need air flow or they will pit and fail. I’m going with something close to this video. Over all a good install OTHER then I have not idea why he doesn’t seal the screws into the stringers!! To me that is a failure waiting for water intrusion.
https://m.youtube.com/watch?v=8m0sVshBrXQ.
The poly tanks I’m no export on but I would think it would be no different. as along as it’s well supported on the sides and bottom.