Fishing Rod,
It is generally agreed that the only measurement of gape that matters is the width of the gape. Laterally compressed prey are swallowed laying flat in the mouth.
Speaking about longnose gar particularly. I have hooked many very large gar of this species using a streamer fly no longer than 1.25". Wasn't really fishing for them but they took my offering in search of a creel of sand bass and other fish. They are hard to land. They want to take the fly with their forcep like mouth and just the tip of hook is barely engaged in that boney part of the mouth. You have to keep the line tight and that is very hard to do when they jump free of the surface shaking their head. They almost always get off. You can use frayed nylon rope to as streamer material and I have had mixed success that way. The fuzzy frayed rope can catch in the toothy mouth but you still have to play them.
