From my experience, Bill and Jane's observations below are spot on. The shallowest part of this unofficial "waterway" from Coon Key to Naples is found just as you approach Goodland, in sight of the two marinas there, one of which, Caloosa Island Yacht Club and Marina, is a SALTY SOUTHEAST CRUISERS' NET SPONSOR!
The message below was copied from the AGLCA list.

Thanks to everyone who gave us advice on taking the inside route up Coon Key Pass.  Be sure to go on a fairly high tide and at the Marco-Bear Point bridge, note that red 26 is way over to the right, just
before the bridge.  Pass 26 on your starboard and then parallel the bridge until you get to the opening.  We also would not recommend Factory Bay Marina at Marco Island on a weekend.  A shoal requires boats to pass very close to the docks and the no-wake zone is almost universally ignored.  It is especially bad around 5 o'clock when the rental float boats are steaming to get back to Marco Marina.  We were there during the week and can't imagine how bad the weekend would be. It's a shame because it's a very nice facility and close to a number of restaurants.
Bill, Jane and Daisy Stone