Congrats on your sheep! We have only hauled ours for a little over an hour, they were ok. We got our ram last summer when it was hot and went real early in the morning when it was a little cooler.
since you are in maine the heat shouldn't be a problem but do be sure to have hay for them to munch on and a bucket for water if there is a problem on the road. mine were about 2 hours away and did fine on the trip. I raise katahdins too and really enjoy them. what are you going to do with them?