My two penn'orth of advice on fuel.
Diesel doesn't go stale, I've seen engines left for 20 years and they cracked off just fine.
From experience with trucks, static engines and boats fuel systems over 40 years I would highly recommend that you go against convention and draw the fuel from the absolute bottom of the tank the same as a truck does.
You NEVER EVER see a truck tank with sludge or water build up in the bottom of the tank as you do on a boat.
Boat builders logic sometimes baffles me.
Draw the fuel from the very bottom of the tank and any impurities will be caught by the primary filter/water separator and the engine pre-filter. That's their function.
When building the new diesel tank for my boat I had it built in 316 Stainless Steel with a bright annealed (mirror) finish on the inside. 2 baffles with offset apertures and an inspection hatch over each baffle so I could access all sections of the tank if necessary, it cost a bit more but it was a case of fit it and forget it.
Peace of mind is priceless..