We have an ancient long shaft Honda 7.5 with sailboat (slow speed)
gearing. With it, we planed at 11-12 knots with 1, 2 or 3 adults
onboard. We didn't get on plane with 5 passengers, about 1000#, but
still moved smartly.

According to Portaboat the maximum safe operating weight is 670 lbs. I can't
see how 5 200lb folks aboard would be a good idea.

http://www.porta-bote.com/dimensions.html

RB