Crab patterns (merkin and kwan), spoon flies, redfish toads, etc will work for redfish. You can talk to Tony or one of his guides at bay street outfitters and they can give you a selection. I use an 8wt with 7.5 foot 20 lb leader with about 18 inches of 20lb tippet (this set up leaves me with a 9 foot set-up and the tippet on the end allows for tying on flies without shortening the leader too much. I just tye on more tippet when the tippet gets short and this prolongs the life of my leader).
The high tides next week are not particularly high, and run from about 11am to almost 4 pm by Sunday. Keep an eye on the water, if the wind is right it could blow extra water onto the flats making that 6.6 a 7.6 and better for tailing fish. If you have access to a boat or kayak you can try fishing the mud flats at low tide. The morning lows would be best and you might even see some tails in the low tide flats.
I don't really ever get on Fripp so I do not know of any spots there, but I have heard from reliable sources that there are plenty of spots on and around fripp...try google earth.
Talk to Tuck Scott, a guide at Bay street outfitters, I know that he fishes around the harbour river area and he might be able to give you some location tips. Let Tuck or Tony know that John Holbrook recommended that you come in.
Good luck and tight lines.