12V Sailboat Circuit Design

I need a clear, reliable 12-volt circuit worked out for my small sailing boat. The system consists of a Lifepo4 house bank of 2x150ah to be wired in parallel, an AGM starter battery for a Volvo Penta MD5 7,5hp diesel engine, the panel is philipi stv 110, there are 10-14 loads to connect... (Budget: €8 - €30 EUR, Jobs: Circuit Design, Electrical Engineering, Electronics, Microcontroller)