WC,

First off.....I'm not a flyfisher so take this for what's it's worth.

In my experience messing with the drag during a fight is not a very good thing to do. I keep my drag a little on the loose side and use a hand if I need to. Once the fish isn't running, then a drag adjustment can be made. Can you palm the spool on the outside rather than getting whacked by the handle?

In any case, you hand is a better gauge of how much pressure to apply than an in-fight drag adjustment.