I know you mentioned BHB may be out because of only 1 tank, but keep it as a backup because the dive would be much longer, 90 mins to over 2 hours. Depending on the tide time it could even be done after boat diving although for me that's a lot.
One of the things I learned after moving to Florida is to move past my ‘must do at least two dives a day’ mindset. I am more than happy to do a 2 to 2 1/2 hour dive at Blue Heron Bridge and call it a day! After all that’s as much or more bottom time than most cold divers get in three dives or more.