you said you have 'several days',, how many is that? flying from AC back to the BC sounds like your best option.
i have no experience north of BZ city so i can't say about corozol area.
if you can find a boat to Pla, it will add at least 2 days to your trip as they stop and spend the night somewhere along the way.
personally,, i think you will be happiest if you fly to BZ city and rent there. then just drop it off on the way out.