Unfortunately I don't see an exact answer to your question. Too many vonlariables.
For example, if you only plan to go out the inlet in calm conditions then a draft just under 6' would work. However, if there is a 3' swell in the channel then you could be bumping bottom with a 4' draft.
Then there is the kind of boating
you plan. Will you go out often for short trips or occasionally for a longer trip? If you want to be able to go out of the Boca inlet any time you have a few hours to spare then you would want to go with a much shallower draft than if you go out less often for a longer sail. Then is your boating
schedule flexible enough that you can time your in and ou with a rising tide. Would you want to consider the option of running up the ditch to Palm Beach?