they need more like 4-5h out per day (unless they have an attached run, in which case they should have 60+ square feet to not need time out of the cage/hutch)... though that wouldn't stop the chewing, unfortunately.
bunnies are project-oriented, and his current "project" is to destroy the hutch. you can try rubbing Ivory soap on the areas he chews (if you don't have that brand, look for something that has no fragrances or dyes) - that works for some bunnies. failing that, you could cover the areas he chews with something like chicken wire, hardware cloth or coroplast to block access.