This time of year in Woods Hole passage we get larval crabs by the jillions and two inch squid as well, the schoolies tear them up. The larval crabs are neat 1/8 of an inch across and perfect imitations of thier Moms and Dads.
I have a flyrod, don't use it as often as I should. I haven't never tried a crab pattern. Just saw one online since you mentioned it- Simons hover crab, looks like it would float nice. May have to order a couple.
Somewhere in the back of my addled brain I remember someone saying a wooly bugger is the fly to use during the crab hatch. So maybe you fly folks can try that. Personally, I think some major white water would improve things.