Was your battery secured to the galley floor or just resting on it? This unfortunately seems to be a recurring problem.
If you don’t mind a few bolt heads on the cab side of the bulkhead wall or can hide them behind a TV screen, I would recommend a simple solution by bolting it directly to the bulkhead with a bolt in battery box. (See Image Below)
If you have the money Lithium is a great choice. There are many more reasons Lithium is superior besides being 1/3 the weight.
https://www.powertechsystems.eu/home/tech-corner/lithium-ion-battery-advantages/
Have you calculated your required Amp hours? If you really do need a 12v 100AH battery it’s likely a Lithium battery would cost you $600-$800
