New to RV's but not really

Well, we have looked at many trailers the last week or so. Lots of way overpriced undermaintained stuff out there. Everything we have looked at we have compared to the 309bhss we first looked at. Nothing seems to compare. Anything from the cabinetry to the solid flooring and lack of delamination of the entire unit is very reassuring. We went and looked at it a second time and I did a more thorough inspection and found the wheel wells are not protected. It seems the curbside wheel well has some damage to the water barrier in the under carriage. This has caused a small section of the flooring to separate and rot. I'm not sure how far the rot goes, if at all. I'm thinking of the floor joists are good then it is just contained to that area. If it is, then I'd think injecting epoxy into the separated wood would be a good repair. If not, then a floor replacement would be expensive due to that it's on the side where all the appliances and cabinetry are located. If that's the case, it would be several thousands just to repair a section of floor. I'm thinking I'm going to get under there with a flashlight and see what I can find. Maybe see if I can remove some drawers and see if there are any soft spots. The floor is rock solid though. I can't imagine there being much damage under there. I've learned that tongue and groove 5/8" OSB has been used in this years model. I'm not sure how I feel about that. Our sandpiper line had 3/4" tongue and groove ply. Thoughts?