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.