hubby and i had a bit of a spat last night over this. i finally told him to just get rid of that wood period. i don't really care how he does it, just do it. i had to go back and forth in my head for awhile til i was ok with which ever way i went.
i think hubby just doesn't want to cut into that wood. must be a guy thing.
i was thinking about the spray foam if i left the wood on, because one side of the wood fits into the box fine, but the other side does not, and there is a gap, so fillers of some type i thought would have to be used.
i am happy with the decision to get rid of that wood. getting rid of it was the intent all along. but this reminds me of when i bought the rv to strip down and start from scratch, and then hubby and i started argueing over that. and then i just decided to give it to him and build my teardrop (the foamie was due to us argueing over that stupid rv). now we are argueing again. but things will work out on this one because i am not giving this to him. i spent more on this trailer than i did on the rv.
i get so annoyed at him sometimes, because i am the one that sits here reading everything i can about this stuff. i take all different ideas, methods, advise and what not. i watch tons of you tube videos, i read all these threads and links that are posted. i search out on my own different ways/methods/materials. and then i make a decision that i can live with and feel pretty good about. then hubby comes along without any ideas what so ever and says my way is wrong, or puts doubts into my head. again, this must be a guy thing. he doesn't know what a torsion box is, he doesn't even know what a kerf is either. he still doesn't get the idea of what i am trying to accomplish with the foam. i thought i had him convinced a year ago, but i guess not.
maybe i need a few more of these today.

and he needs a few less of these
but the decision has been made: the wood goes. i need that weight somewhere else. and since there is a box like frame, i am going to build the floor to slide right into that box. (i hope anyway. i may end up using some of that foam spray).