By chip board, do you mean OSB (oriented strand board)? There are other products made of compressed wood fiber also. Some Airstreams have used OSB as a subfloor, but I don't know if it were done so long ago as 1987. OSB deteriorates substantially when it gets wet and may need replacement. Some other compressed wood products may or may not be damaged by water. Have you been able to check out the condition of the bottom side of the boards to see if they are good?
If it is ok, then I would paint it with marine quality paint to thoroughly seal it.
There are many threads about subfloors and flooring and I encourage you to search for them and check out the Forums page and look for the subforum under Restoration for floors. You will learn more than you thought you ever would need to know.
Once you figure out what to do about the chip board, you can start thinking about flooring. There are many options including cork, vinyl, carpet, rubber, laminate, solid wood. They all have advantages and disadvantages. Weight is an issue as well as whether they are easily damaged by water.