Additional batteries might be more efficient as opposed to more fuel, since your generator seems to produce surplus electricity. Also i'm not sure how it could be done, but an automated system that shut off your diesel once your batteries hit 100% and then switched them back on once charge dropped to something like 75 or 80 percent would save fuel.
An automatic generator is pretty simple to make. You can make the throttle be the inverse of the battery charge +1, then for turning on and shutting off you can use “less than” to and “greater than” blocks. Basically make a couple conditions for the engine to run. If the key is on and the battery is less than “x”, turn the engine on. If battery charge is greater than 0.99. So, less than, greater than, and I reckon maybe a push-to-toggle might be the way to go. I’d have to look at my MC for it again.
Its really annoying me that water comes into the bed of the truck without it going over the sides, would be really nice if it was all inside a water tight cabin 😕