A couple thoughts:
1. Do you think factory wiring between alternator output and battery could be improved to any significant degree?
2. Did the truck have a dual alternator option? Maybe you can set up something as your second alternator to do what you want. Either add charge rate to existing battery or split off the new alternator into a dedicated house battery (if system doesn't tolerate what you're after). I can say on my class C, running the solar panels at 14.4 volt and feeding that to Ford's chassis system, I don't get any check engine lights.
