Best Solution for Waterproofing Exposed Floor Joists Above Shower?

Hey r/homeimprovement!

I have a basement where the floor joists remain exposed. There is a shower down there with one section (approximately two feet wide) that is exposed above the showerhead. Picture here: https://imgur.com/CQyKM7M

When the work was originally done, the joists and exposed areas were painted and coated with some kind of clear wood sealer. After about 2 years of regular showers down there, it's clear that the sealer is starting to wear (as is the paint below it).

In about 3 months the person who uses that shower regularly will be moving out, and I'd like to take the opportunity to re-caulk the shower, and while doing so, try and implement a slightly better solution for the exposed area, since that shower will be vacant for some time (and may only be used by guests in the future).

Any brilliant ideas?