You will be using your dinghy
a lot more than you expect and for a lot longer distances in rougher water than planned. The common engine size of 9.8HP (2-stroke) is sufficient for one-three people in a small dinghy
. I would recommend getting a hard-bottomed dingy rather than an inflatable bottomed one, it will make life much better in the long run. Aluminum bottoms are lighter than fiberglass, but the common Caribe or AB models with fiberglass double-walled hulls are great and only a bit heavier.
I regret having gone for a soft-bottomed one this time around - particularly on long rides, i.e. from Marigot to the far end of the Simpson Bay Lagoon in St. Martin (a couple of miles in a mix of choppy lagoon waters and deep-swell ocean ones.