Yammy 90 on my 1875 ProGuide drops to a troll speed of 1.4mph using the RPM limiter. As the hours build on the motor, you will in colder water build carbon up pretty quick using that limiter so run it hard back to launch and burn that out. The Terrova 80 will pull the boat along for a troll at up to about 2.6mph.
Cruise speed at 4500rpm is about 27-28mph. Go a big tiller, lots of room to roam.