Yes...you will go through lots of yummy treats.
That's fine feed him a bit less of his meals.
Let him drag his leash around the house when you are supervising...and leave his collar on except when he is in the crate.
Have you got another dog that he could go out with? This may just give him his confidence back...or he will be so occupied with the other dog...he will forget what he is scared of.
Gina