I think the key is to find a lake where the walleyes are in water
shallower than 30 feet so you can get to them.

I was not using a fly rod, but did recently go walleye fishing on Lake Erie.
If 30' is the upper bound for deep water fly fishing, then it would have
been possible for me...the deepest we fished was about 30', with most being
in the 20' range.