I am in a similar situation, and I took the back 4ft and front 4ft off exposing the frame. The whole inside is gutted [59 Tradewind] and I have the luxury to see the floor. I went around with an ice pick to check floor and although not in the best of shape, I can get away with just replacing the back and front [with frame welding...].
I would look up front and take a look. The problem is once you start looking...it never stops. I have just the right amount of denial, lack of funds mixed with safety in mind to not make this a 2 year project. But I am using it for a studio, and not camping.
Those that think they know don't know, those that know they don't know, know.