Interesting reading through the comments - a few things stand out to me that you might want to consider further:
1. Thinking that any Kodiak will get 3 nmpg is fantasy I think. For roundtrip averages, even regular GAs have difficulty averaging that on full trips consistently. Lindy's Kodiak, which he built heavy with lots of fancy hardwood cabinetry etc doesn't even get 2 nmpg right now with his brand new twin 175 Yamahas. So if it was me and you're building light and smart, I'd plan for no more than 2.5 nmpg and maybe even a bit less.
2. I'm curious why the generator? As an electrical designer/installer, I've now talked 3 clients out of generators and instead got them into good lithium house batteries and solar systems and they've loved that setup universally. The Kodiak has tons of roof space for solar panels.
3. House batteries way back at the transom sounds like an awful lot of weight/congestion back there, especially with twins, plus larger cable sizes needed to get to the main helm panel. Plus that takes space where you might want a washdown pump, bilge blower, final negative/ground/bonding bus, start batteries, fuel system parts like water separator, valves, etc. etc. My favorite place for batteries is just aft or just forward (in the case of lithium) of the aft cabin bulkhead. This puts them closer to the CG of the boat and in a convenient place for wire runs.
Keep up the good work, this is a fun one to watch!