Replacing swollen wood on slide out bottom (outside)

Good luck with your band-aids - totally understand considering the weather. Further, and worth exploring for yourself, it that the manufacturer will build you and entire new slide out box ready to install if you are will to pay for it. I say this since you also know there's damage in the wall. Keep in mind that is composite construction, and the strength comes from having a solid, intact sandwich. Since you got a 5er, a trip out to the factory for a pre-arranged repair could be very realistic...