North fork boat ramps
Mike, the one your thinking of is the NYS DEC Access site, at Oyster Ponds. It's pretty much a useless ramp that is always filled in with rocks and almost impossible to launch on.
The ramp at the end of Narrow River Road is also a NYS DEC Access site. And again, it's a barely usuable stone beach ramp, that I almost got stuck launching my 14' jon boat at.
No permits are needed for either the the Oyster Ponds or the Narrow River Road launch sites, but they are not good for launching a boat of any significant size.
Getting the Southold Town Non-resident permit is costly now, at around $100, but it gives you access to a lot of ramps. Gull Pond at the end of Manhasset Ave, to fish Greenport, or make the run to Orient. But for the $20 launch fee they charge at Orient by the Sea, I think I'd rather save the time, and probably $20 in gas in the boat, to launch at the restaurant when fishing Plum Gut or the Race. New Suffolk also has a nice ramp to fish Peconic Bay. There are a few other boat ramps that gives you access to also, but those are the only two I've used out there.
The DEC also put in a decent boat launch in Mattituck right by the inlet, that is free of charge to everyone, but it has funky hours, so you may want to call the Marine Habitat office at (631) 444-0311 to see what they are now.