I can get that speed out of my 42lb thrust Motorguide .... ProCraft 16' w/90Merc + about 500lbs of anglers & equipment. Boat is very heavy for it's length (1700lbs dry weight) but is very buoyant (bounces from small waves, blows/drifts easily with moderate wind). I get that speed with big motor still down, so I might get a bit more speed with it trimmed up ... but I'd probably lose a bit of tracking control in the wind.

Even when I'm Pushing .... 1mph is about as fast as I go. But, I'm only running on one 29series battery.

If you need more speed & longer battery use .... I'd look at getting a 24v variable speed TM w/80# thrust.