help on selecting a kicker

Short or long shaft depending on how tall your transom is. For that boat a 9.9 should be perfect. A smaller motor would work but having a backup that will actually push the boat is a real benefit.

I have a Merc 9.9 4 stroke on my 20ft and its perfect. Slow troll about .8-1.0mph or almost plane the boat with just me in it. top end about 10mph.

My Dad bleeds red white and blue and has been a Johnson/Evinrude man his whole life. Last month he bought a T9.9 4 Stroke Yamaha and he could not be happier. It is electric start and electric trim and is high thrust. He used it as a kicker for two weeks in Ontario on his 1775 Pro V Lund. Shoot me a PM if you might be interested and I can get you the dealer's name and number of where he bought it (somewhere in Florida).

To answer your question, a 8 or 9.9 would be good for your boat. I would recommend a long shaft for the Saint Clair Chop to make sure your prop is always in the water.

4 strokes can be very heavy, however check out nissan or dihatsu ( Iknow there foreign) but they make the lightest cheapest 4 strokes. I don't think you need to go to a 10 horse, but you never know, you might upgrade boats someday. Thats my two cents.

i would go long shaft i ve a 8hp 2 stoke on mine 17 ft crestliner and works great for trollin for eye and muskie

I have a 50# thrust electric transom mount on a 15' glass bow rider and really like it, cost about 200 bucks and will go from .8 mph up to about 3.3mph in forward (on gps), if you can mount a bowmount I would use that but you need some thick glass to support it, in case your interested,
do you have a swim deck or are you planning on mounting a bracket that will make a difference between a short/long shaft
an out board on your transom may change your balance on a shorter boat and will cost a bit more than a lectric, but they are nice, hope this helped.