Yeah, if I can find a 50W version, that will be the ticket. Traco has a high power product line as well, with an input range of 9-36V, but the nominal is stated as 24V. Even though it's listed as 9-36, but I don't know how the output would be with going that far below nominal. Here's a link to that one.

I'm going to talk to a couple of the electrical engineers at work this week, and see how hard it would be to make up a simple 50W DC-DC converter, with an input range of something like 9-14V DC.

If I want to get fancy, I'll have them design it with a potentiometer on the output, so it can be dialed down from 12V to 11.5 for the break in / under 2 gallon setting that Eric recommended. Probably overkill, but I'm an engineer too (mechanical, not electrical), so coming up solutions to problems like this is kinda fun for me.