Here’s some info. Based on the posted schedule it appears that there are normally 2 commercial flights a DAY out of Hagerstown so I am guessing it won’t be crowded. I fly out of a couple small regional airports (not that one though) and they are usually very easy to deal with. But be aware that often the crew checking luggage is the same as the crew helping to board the plane so you don’t want to be late because they will have left the front desk.
http://www.flyhagerstown.com/traveler_info/index.html