I always have run a second. It will cost you a bit more... but who knows, maybe you don't need to??? Your decision. Easier to do it up front then pull it back apart, though. I will say that most of my experience with dock power is in a salt water environment so it is corosive on the wiring - thus, poor electrical feeds from shoreside.
80's in the summer?? Phew!! You will be FINE with 16k!!! Shoot, when it is in the 80's here (Texas) and S Florida, I am pulling on a coat and shutting down the hatches (just kidding, a little). And with the reverse-cycle function, you can heat and really extend your cruising range.
Best of luck.