Floor repairs are common. Segmental replacement has been done. Dry rot is a misnomer -- water is causing 'wet rot' and getting in through one of several routes. Describe your specific location and we'll see what we can come up with. A hearty welcome to the Forums! I know it is a bummer when summer comes along and you have to start making lists of things to do before you're fully functional. But at least it might be usable before then...
Ahh, Bandon .... It's nice figuring out different locations. Near Steve Prefontaine's hometown of Coos Bay. VA Medical Center down in Medford... Pretty area!