We did the trip in April.
We went from Marathon to Key West in two days. Spent the night on a ball at Looe Key - it got bouncy.
From KW we went to Boca Grande Key to shorten the distance to Dry Tortugas a little. There are some pretty good tide rips there.
I took advice from a bunch of people in Boot Key Harbor and went outside. There is a lot of shallow water on the bay side and no places to anchor if you need to, from anything with North in it.
Not that there are a lot of places to anchor on the E/S side but there are a few. The last one is Newfound Harbor which is at Big Pine Key. Or just NW of marker 7 in Niles channel.
I don't think you can anchor at Boca Chica because of the base there.
If you are in Big Pine and go the Bay way, you go back to Boot Key, N into the bay and then all the way to KW - 3 sides of a rectangle.
If the weather is fine then it would not be a problem. If anything N sets in it will be uncomfortable as the chop builds up and you've no where to go. I don't think the snorkeling can be as good as around the rocks in Hawk channel. And there are lots of rocks close in.
From Boca Grande to the Tortugas we cut the corner after the Marquesas and went over N a little to barely skirt Rebecca Shoal and where there was supposed to be 7-8 ft of water (or 4
)we never saw less than 14. I guess that is why they call it The Quicksands.
We had NNE 20-25. What a ride.
First night in Tortugas (where the marine radio usually cannot pick up NOAA with any reliability) the fort recorded 42 knots sustained for 45 min. Whew, am I glad we were sleeping or I would have wet my pants with there being rusty steel pilings 15-20 seconds away if the boat went free!!!