Outboard vs. Inboard
When we were younger, poorer, etc. we cruised the Chesapeake and later the whole ICW aboard a Flicka (20'' LOA) with only an outboard. Friends on a sistership cruised the Bahamas comfortably with nothing but an Italian outboard for power. (If you want to live on the edge, mechanically speaking, try relying on a 1980 Italian outboard...).
I think the main disadvantages of an outboard for your plans are the absence of decent electrical generation and the high fuel consumption. Fuel is not readily available in much of the Bahamas (or quite expensive) and not at all available W of Key West. If you are route planning between the Bahamas and Ft. Myers, you''ll be tempted to consider using the Okeechobee Waterway in at least one direction, but that''s a lot of hours of buzzing. As for electricity, our Flicka was very basic but we still found the little alternator on our Honda outboard inadequate.
You may wonder why, in the presence of ''chop'' which suggests wind which means you can be sailing, hobby-horsing and clearance of the prop from the water would become an issue. There can easily be a cut in a reef, a small channel in the ICW or a narrow channel in which you must motor (no room for tacking) directly into the wind. It''s at those times the entire crew is sitting on the sterm pulpit, trying to depress the stern. OTOH a diesel will increase purchase price, increase maintenance costs, increase ''gear liability'' if not relatively new, increase overall weight, steal valuable storage room on a small boat, and be too close a neighbor to live with on a small boat. There are inviting reasons to avoid an inboard.