There's only a few places around here I know of where you can catch decent crappie with a fly rod. Most are too deep like you said or no bigger than sunfish.Crappie here are so deep, I have a hard time getting down to them without sinking tip line and split shot. Takes the fun out of it.
I did catch some walleye on streamers back in Eastern Colorado years ago. The old Zonker pattern with black died rabbit fur strips along the back and a tubular Mylar body. I’m guessing they’d hit most streamers, but that was as close to a crank bait looking pattern as I had.
I'll have to find some patterns like that. I want to perfect my streamer fishing so I can get some of those bigger browns and bows. Trying them on these eyes might help out.