Just to clarify - I am NOT considering foaming the tank in. Hazard of mentioning two independent thoughts in one paragraph :)
I am going to go with a poly tank - a Moeller FOLT5007 -
https://www.oceanlinkinc.com/product...0-25-folt5007/ I have a gameplan of how I'm going to mount it, but waiting to detail the method until I have it in hand. I may wait to do the tank till spring. Not sure yet.
The foam I was referring to is the flotation foam down the side cavities either side of the stringers. If I'm gonna do it, best to do it while I've got it in 2 pieces. Just struggling with the decision either way.