I've never seen caddis back here in the east in the numbers you describe. I did get to fish the mother's day caddis hatch last year on the Green River, we floated the lower part of section C. What a day we had!!!
We fished them with an x-caddis dry. It worked all day. You might try some of those for a different, yet effective pattern.
The only fly hatch (super hatch) I have seen back here in the east is the ephoron leukon, white mayfly, hatch on the Housatonic in August. I have seen it so heavy that I could barely make out the shore line across the river, approximately 100 ft away.