Adding Outlet to Poly Fuel Tank?

Due to space constraints in my boat I am looking to ditch the portable tank setup and buy/make something that allows me to better arrange my fuel tank, batteries and oil tank. I had my heart set on making an aluminum or stainless tank (since I already have all the necessary materials on hand) until I saw this tank: https://www.pacificcustoms.com/tank0833ep-blk.html

That would work perfectly (size/shape-wise) for me - however, the fuel fitting on the bottom of the tank is 1/4" NPT, whereas my fuel lines are 3/8". I can plug the existing outlet easy enough, but I wasn't sure if anyone on here has experience adding an outlet to poly tanks?

You don't want a gravity feed fuel tank on a boat. If something fails your boat will fill with fuel and you will be sitting in the middle of it..

Touche. I hadn't thought of that #-o