i have a 8hp merc on the back of mine,and for a backup it is it.for trolling,it gets down to 1.1mph,if i need to i throw out the bag or the 2 5 gallon buckets if need be.
the best thing to do is see what you need,in the line of hp restriction lakes and such,then go from there.around here in pa we have 10hp and under lakes,so that and the price i paid for the motor was my deciding factor.i got remote throttles,and steering connected to the main motor.it pushes the 19 around 6 mpg on the gps,with the present prop on it.
mounting it on the straight transom was a bracket all its own,for your transom,you will have to find another like it with a kicker and see how they did it.my shaft length is barely long enough but works out great.mine is plumbed into the main tank,so no worry about running out of gas unless dummy forgets to put gas in it,but also no kicking around the tank for the kicker either.