Yes, make him fend for himself, save for the flight. If he bags the whole trip in over having to pay for his own room and chow, then he's an idiot (well, he's that regardless).
IF he were to bag the trip, you would have to buck up and tell the boys that Daddy just couldn't make it happen this time, and hope for the best for another time.
At the end of it all, it is your call. I know you want to do what's best for the boys, but just remember, a stressed out Mommy isn't much better than a dead-beat Daddy sometimes. Good luck to you!!