I've looked into doing the whole "rent my own boat for my dive group" rather than going the way of the dive charters.
Most if not all boat rental places will not allow the use of dive gear on their boats. Sure I guess you could break their rules and do it anyway but that comes with it's own potential downfalls.
Just as I did you're probably better off giving up on the idea and just booking a private 6 pack charter for the days you're looking to dive. Then you get the benefit of an experienced Captain who will take care of all the logistics and headaches and it probably won't cost you more, and possibly will cost less than the boat rental would have been.
Note that full boat charter prices vary significantly. In my dive notes for Florida Keys, I've got Quiescence at $450 per half day and Sun Sports Islamorada at $750 for a half day. I've never dived with Quiescence and probably never will despite them being highly rated and reviewed, because they've got a rather odd and restrictive policy of only one deep dive per day and I'm all about the wrecks. I've never dived with Sun Sports even though I booked with them once because when they told me the price I was like "why so much?" and they said it's because of their concierge service.. yeah that's ok I'll bring my own sandwiches and save the $300 (or about double that for a full day charter).
If you're diving from Fort Lauderdale to Pompano check out Miss Conduct charters. Conrad will run his 6 pack with a 2 diver minimum, 6 diver max, and he'll take you where you want to go. I suggest you avoid Seefish charters, I've had bad experiences with Brett changing requested and promised dive sites last minute and canceling dives the night before for 'unexplained personal reasons".
Don't know of any private charter boats in Boynton or Jupiter but the area dive Ops don't tend to be of the "cattleboat" variety even though in West Palm, Pura Vida can load up their boats with a good amount of divers from time to time.