I would continue doing what your doing...be consistent with it and he will stop...Dog have very short memories...so while your training him what you told him yesterday is forgotten the next day until you reminded him...And its very nature to wanna protect his den "crate"...I would just put him in his "no bite" position before touching or cleaning his crate...and after a while of training he will get what you want...You are on the right track
Good luck!