I get what you are saying. There is a closed systems that have Gar in it that need to be removed. I won't make a dent in the population with fly rod, there are just too many and need electro surveyed, but I do want to pull on them and haven't done well with regular flies. Mind posting up some pics of flies that have worked for you?
Completely understand, and if they fish are going to fish heaven eventually, I say go for it. There are tons of rope fly recipes out there.
Two conventional patterns I've had success on are
Zimmerman's backstabber and Matt Bennett's lunch money. Most of the gar I've caught have been in the hill country while fishing for bass or carp. As I said earlier, it's sight fishing because if I can see them, I know I can get a fly in front of their face they will react. Both of these have stout and short Gamakatsu hooks so they're going to set in a bony jaw.
I also learned (mostly by accident) to set the hook a bit slower. It's tough to do because you'll often see the take, but instead of a quick strip like you would for a bass or redfish, a smoother (but not slow) allows the hook to find something to hold onto in the fish's jaw before simply sliding off.
Hope that helps a bit!