RE: cooling with fuel pump?
Hi Rye,
Keep in mind most fuel pumps are not designed for continuous operation, running it on a lower Voltage will surely help keeping the (pump)motor temperature down, but keep an eye on it anyway.
Even if you're not going fast, with intakes behind the props and a suction outlet, you should have flow through the cooling system, without a pump, even when just crawling along...
Regards, Jan.