Isn't the Casita
floor a layer of wood sandwiched between two layers of fiberglass under the vinyl? That means (I think) you have to cut away the fiberglass, replace the wood, and repair the fiberglass.
Second, 24" is a pretty large area. I am wondering whether you can just replace the damaged area, or whether you need to do an even larger section, back to a frame member, maybe? And will you have to take out some of the cabinetry?
Last, I haven't read too much here about floor repair on Casitas. It strikes me as unusual on one that new. You might take take the question to the Casita
forum, where there seem to be more technical discussions.
Casita Travel Trailer Forum
All in all, sounds like a pretty big red flag to me.