One of the best strategies if you will be going out is to put the treats in the crate a short time before you leave and lock the dog out, so he can see them but not access them. Hopefully by the time you are ready to depart the dog will be anticipating getting into that crate and enjoying his treats! This can work very well and result in a dog that is looking forward to you leaving.
I did something similar with my dog's roller ball, loading it up and making him wait for it. This dog that formerly had separation anxiety would become impatient and sometimes baroo to tell me he wanted me to leave so that he could have his ball!