Re: Temp vinyl flooring over polyurethaned oak.
This is the only time I will ever recommend this, but I think it's the prefect situation for a floating laminate (pergo-type) flooring. It would be applied over that foam-polyethylene underlayment, and the glued joints will exclude any leakages. When the time comes to restore the room, the original floor underneath should be unaffected. It's only fastened down by the shoe molding, essentially. It is very cleanable and hygienic. My only concern is that it may be slippery, but perhaps there are different grades of slick finish available.
Remove not the ancient landmark, which your fathers have set.