Looking for a master key for my Holiday Rambler

Gas cap door and water is easy. They are what's called cam locks and they are cheap. Take them off and most lock smiths can rekey them or replace them. They are less than $10 each.

One less key.

Trimark door lock is pricey. I only use one lock, don't carry the dead bolt key but have a full set hidden outside.

One less key.

Why carry the ignition key when your not driving?

One less key.