The 2nd last tournament we went to, 2 of the adults (one was a coach of the 12U team) were totally plastered. The one guy thought it was funny to get his BMW up to 100 MPH on the way back to the hotel after dinner. the coach was so drunk that he had no idea where his 12 yr old was (and x-wife/mom was not there). I just looked at my husband and said, "You know that if you took our 12 yr old 400 miles away from home, got drunk and had no idea where she was, I'd kill you, right?" I knew he never would...but to answer my question, he held up his can of Diet Coke. The next day, the 100 MPH Dad was offering to keep a couple kids an extra day and go to an amusement park. No way, No how would I leave my DD with this man. He had already proven to me that he is not the kind of man I would trust to make good decisions....and he wasn't getting the opportunity to make a bad decision with my child.
So, yes...I think it is absolutely reasonable and actually the only responsible thing, to be assured that the people that will be watching all these kids are sober, background checked (as all coaches should be) and given a list of expectations/rules. If they have a problem taking on that responsibility, then the kids should be with their parents.
Jess