I'm really curious why you would resin the inside of the box.
I know you said it was rough but you could have easily just
sanded the ply or laminated a 1/8" hard board over the rough
surface gluing it in place giving you a smooth surface or even
sound deadening material. Honestly, its not a necessity to be
perfectly smooth inside. In fact in the end you may benifet
from having fill in the box if you happen to have port noise.
Neat build, MASSIVE sub.