Repairing soft floor in my wolf creek

I’d think about adding starboard or aluminum plate. 1/4 inch is pretty thin. Depending on how hard it is to get to the floor, I’d try to replace as much as you can. There is also many different finishes of vinyl flooring that could be used to update the look to even a “wood” flooring look if you wanted.

But, before I’d do that ... I’d call the manufacturer if not for them standing behind it, but at least for information on what they think is the best way to fix it.