A HomeDepot Tour - and two hours later - Fake a Lake works perfect vs 5 gal pail -
or forcing impeller from having to suck the water out from a pail.
Strictly full gravity easy flow.

Chrome plastic fitting is bathroom sink drain modified for water inlet at the sink drain control port - the elbo was Dremeled out to slip over drain control set with epoxy - The same was done to the water to engine ball valve.

The Portion of pipe cut off the drain was used on the valve output, then spa hose simply slips on - also slips on impeller pump inlet with no clamps needed.

The bulk of water standing in slim line waste basket easily feeds engine with low water source from well - and will fill at idle - but rev it will drain it fast -

I trimmed the large ball valve on the ends to make it smaller profile.

When engine is shut off after running 20 minutes to get the oil warmed - the water tank valves can be shut off w/o running to the source and loosing water from running into engine and general leaking w/o clamps used.

ABS 3/16 panels were made for moral support on both sides of basket to support the valve combo and weight of water.
Small screw pilot holes were made to keep the panels aligned before epoxy was applied to the inside panel.

Let it set up good - then hole saw for the drain - modified inside threaded ring to use a O-Ring.