Taken one trip in a MNIII-

All three should paddle - it is fast.
That being said the stern paddler should be ready for a surprise on that first drift into a portage landing, the momentum carried by three people and gear is tremendous.

Probably best if only two fish at a time (stern paddler is trolling motor), the third seat is relatively close to the stern seat.

the MNIII likes to go straight- the bow paddler must help in order to negotiate twisty creeks (pries, draws, bow rudders etc).

One trip portages are easy.