That's true. I should probably not sweat it too much right?Everything in life is a trade off.
This can be mostly solved by using a healthy 120 vac to 12 volt charger and letting it run a few minutes prior t o starting.
A relay can be added to power the charger when needed.
A charger is current limited so a much more reliable approach than connecting the DC - DC converter.
Another option would be to keep that emergency switch and one of the house 12v OEM house batteries but move it to the front of the RV (opposite side of the starter battery under the hood) to balance the weight a bit. Keep that battery powering just the generator start and the hydraulic pump, and it will serve as an emergency battery for starting as well.
I'm considering this because they are brand new interstate deep cycle lead acid batteries that they replaced at the dealership prior to purchase that would be a shame to put into storage.