Kicker motor shaft length and mounting plate

[vetting]

Looking at getting a T9.9 Yamaha as a kicker motor.  Having a real difficult time finding a remote 25" shaft used.  I went and measured my transom of the weekend and wondering if I could get away with a 20".  Where I want to mount it, its around 16" from the water line to the bottom of the transom.  However, we often troll in following seas and the waves can crash up another 6 inches above that.  Just looking for any suggestions or help.  

[FishingFool34]

Panther (Marine Tech) makes an adjustable mounting bracket for kicker motors.

https://www.cabelas.com/product/Marine-Tech-Outboard-Motor-Brackets/701688.uts?productVariantId=1215695&WT.tsrc=PPC&WT.mc_id=GoogleProductAds&WT.z_mc_id1=02924836&rid=20&ds_rl=1252079&gclid=EAIaIQobChMIkbaJxrO_2gIVx1YNCh2Bxww2EAYYASABEgI0yvD_BwE&gclsrc=aw.ds

Edited April 16, 2018 by FishingFool34