It may also help to exercise/play hard before you go so he is tired.
On the treat thing, find something your dog salivates for, maybe tiny bits of beef or chicken that you can stuff in the kong or freeze into ice cubes, or put in a treat dispenser. Give them in the crate only. (put the ice cubes in a food bowl to decrease mess, obviously)
If none of this works, then you can do a plan b, which is put in a really large crate or pen with some sort of indoor potty system. Or, try a medication and continue training until no more peeing, then ween off.
