Cutting out chunks of the floor will fix that problem, but won't give you a good look at a bigger potential issue...the frame. If it has been very wet under the floor you may have rust issues, which, if serious, can cause damage to the frame or even cause it to break.
It might be worth pulling back a bit of the belly pan here and there to get a look at what damage that water has done. One of the reasons separation happens is because the bolts that hold the shell to the floor rust or rot out....
This is more work though, but it would make me feel better to know how the frame looked if it was my trailer...