[Billpotter]

I agree with Frizzle on the mechanical fastening and air circulation. If it were me, I'd sit the tank(s) on a platform with an oil resistant ribbed mat under. Front tanks take a beating- more support is better. aluma prep and coal tar epoxy wouldn't hurt either. Don't forget to properly bond fill/ tank/ vessel negative. A-2 fill hose with double hose clamps, no dips; at least B hose for the vent- no dips; A is better. I've checked out the new A1-15 fuel pick up hose- looks like good stuff- basically polyethylene fuel tubing with A1 hose around it- should be a once and done deal: I'm using it on my project. I'd follow all of the mandatory and voluntary standards as required in United States 46 CFR 182.455 and ABYC H-24- available on the web.
If it were mine, I'd try to keep the tank out of/ away from bilge water. As a last attempt to prolong tank life (prevent corrosion) on my 50 year boat, I am installing a flush system (tied into vessel fresh water wash down system) to flush my tanks with fresh water- I installed my tanks in separate bulkheaded tank compartments with one 1" drain hole aft on tank support platform. When tested with regular city water pressure, tank compartments flooded up 5-6". This should wash off any salt off tank tops, and lower areas/ bottoms of tanks.

I went with 50 front/ 70 gallons rear of console step down (all the gas I could fit) to have a built in reserve/ ability to keep/ get weight out of the stern when I want to.

As a good friend of mine reminds me: it's a sickness.