RE:Brewster Flats/Billingsgate 7/3
There are now two ramps at Sesuit Harbor, both (I belive) managed by the town of Dennis. One's on the east side the other on the west both very easy to get to off 6A.
The harbor is very tidal (like all bay side locations) and the ramp to the east is off limits at normal mean low water depths due to a lack of water. The west ramp I used for the first time last week and it was great right thru a minus tide. The channel leading out of the harbor shoals up about 100 yds from the entrance but I think with your draft you'd be fine.
The area surrounding Sesuit fishes well, sometimes you'll see fish busting just 1/2 mile to the east of the ramp and I feel it gives you the best access to Billingsgate (even better than Wellfleet since it cuts out another 35 minutes of driving) Both ramps are open (to the best of my knowledge) 24 hrs and if you launch before the attendant arrives you'll find a note on the windshield.
No need to be critical of the ramp skills, I know you take great care of your boat. There's a lot to think about when launching and loading. I'm still learning every time I get it wet....
Call or e.mail me me anytime if you want more details for that or other locations.