Sooooooo, I'd reccomend patching it up the best you can add lots of dicore and travel all over the place with it..
It does not have to look pretty just function well right ?
Add some treated 3/4 ply underneath to support sagging wood, throw in some anti fungal/ rot, paint and play with your friends and family...
OR
Spend way too much time / money fixing something that MAY not affect the travel worthiness of trailer??
I have to remind myself these things aren't going to be airborne or going underwater so the "danger" of something happening is pretty slight.
Enjoy and have a great Christmas.
-Repo