My RV has wire rated for 15 amps on nearly all DC circuits. I think that would be a minimum. If I were starting from scratch I'd use wire that could handle 30 amps.
The main charging wire from the engine to the house bank is rated for 60 amps.
after the third failure, I replaced the fuse with an automatic reset 50 amp breaker. I deliberately went to 50 because breakers don't give the instant response that a fuse does.
My lighting is NOT all on one breaker. That's a nice feature because I would not be trying to replace a fuse in total darkness.
I've blown just one 12 volt fuse and it was my own fault. I accidentally connected a 500 watt load to a 400 watt inverter connected to a 15 amp 12 volt breaker. It blew instantly--which is exactly what is needed.