I have a 75# 24 volt 5 speed on a 17' tin. It pulls that boat upwards of 3.6 mph with a three blade prop, 3.2 mph with a two blade. Will do this all day long.
I actually contacted the manufacturer to find out how to slow it down, the reason for the two blade prop. If you go digital, you won't have this issue, you'll be able to slow it down to a crawl.
The downside is it's a 5 speed. If it's on 3 or higher, turned to the side, I'm going overboard if not paying attention. Even on speed "1", when it's calm, I have to plan where I want end up. One bump of the switch, I'm really moving. On the upside, wind isn't an issue!
As for spending half the cost of the boat on a tm, look at it this way, that less expensive boat allows you to do this. If you had a more expensive boat, would you be able to do it?
I downgraded my engine, both in years and hp, so I could get money to upgrade the electronics. Best thing I've done, no regrets. The electronics and trolling motor double the cost of my boat. If I had a more expensive boat, those "extras" wouldn't be on it.
Drinkin coffee, missin fish.