A general note: While the depths reported at mean low (or higher tides, if you're taking a "shot" at calculating them) are a FLAT water.
If you have an 18" wake (when measured from the top to the bottom -- vs. the "neutral axis") you're going to go from say 7' of "expected" depth to 6'-3". A little wind or swell -- or some power boat passing you -- and you're going to take a slam.
With 4' waves, you can go from an 8' depth to less than 6' actual every 3 -5 seconds as they pass.
I know that sailboats get in and out of that inlet. My dear (and departed) buddy, Jon Eisberg used to take his boat from his home up the way inside there. But Jon, was very careful and had been sailing those waters since he was a "kid".