My girls chew the heck out of the coroplast floors in their condo. I've tried soap (needs to be Ivory soap or another brand with no dyes, perfumes, etc. in it if you try that). I've tried no-chew sprays. I've tried hot sauce. Nothing works for more than about a day (if that). Rabbits are ridiculously determined little naughties!
The only thing that truly works to thwart naughtiness is to block access completely. For the inside of a hutch, I recommend something like chicken wire or metal hardware cloth. Imo, hardware cloth is better because the holes are much smaller (you can get it with 1/2'' or 1/4'' holes - 1/2'' should suffice). If you ask a hardware store employee where the hardware cloth is, they probably won't know - instead, ask them where the chicken wire is, as the metal hardware cloth is always in the same place. Cut it to fit the inside of the hutch (pressed up against the wood).
As for securing it, I would use wood screws. I recommend 1''-1.5'' screws unless the hutch walls are thinner than that, in which case use the longest screws you can that won't go all the way through. For particularly thin walls, bolts may be a better way to go as they don't have pointy ends and are secured with a nut on the far side of the wall. Either way, you'll need washers - you can find ones that are around 1'' in diameter that have a small enough hole to accommodate a #8 screw or bolt. They don't necessarily have to be THAT big, though - as long as the diameter is greater than 1/2'' (ie larger than the holes in the mesh), you'll be fine.
Place the hardware cloth how you want it positioned on the wall, drill a very small pilot hole in one of the squares of the hardware cloth (assuming you're using screws; for bolts, an actual hole all the way through the wall that's big enough to slide the bolt through), place the washer on the screw/slide it to the head of the screw and then screw the screw into the pilot hole so that the washer keeps the hardware cloth pinned down. Repeat around the outside of each hardware cloth piece (3-4'' intervals are probably best).
Now if a bunny tries to chew the wooden walls, there's a mouthful of metal mesh waiting to thwart them
Oh, and don't forget to make sure there are no pointy edges around the outside of the hardware cloth squares (where you've cut it) that could poke a bunny - if need be, you can use a file to smooth things out.
