No, charging hourly won't work. Some people simply won't play faster. Some people would play slower if only to spite the people behind them (might sound harsh, but someone comes out pissed off from a bad day or week at work and might just feel like making everyone's life suck, at least for a few hours).
I've said it before, there are two kinds of golfers, in general. Those who play as fast as they can and those who play as fast as they want. If a group of golfers playing as fast as they can (assuming this is in the 3 hour range) gets behind a group who is playing as fast as they want (assuming 4 or 4:15 in this case) then the group in back will be miserable, even moreso if there are 4 or 5 groups in front and they can't play through.
Club management in general just needs a better grasp on how pace of play must work. You can't go off the pace rating for the first group of the day, if you do, every subsequent group will play slower than pace and by the end of the day you're looking at a 5+ hour pace. I faught daily to get our pace of play on a better target at my last club, no one listened to me. But charging an hourly rate won't work. Like someone else said, if a group is capable of playing in 3.5 hours and come in in 5.5 because the group in front of them is terribly slow, they will blow a gasket back in the clubhouse when I (or the pro) tell them they have to pay more money because they played slower. Not a very good idea.