When ever trailering the boat with the motor hung on the back end of that motor bracket, the engine will bounce up and down every time you hit a hole, bump in the road and so forth. Suggest that you tie that motor up by the handle to something on the rear of the boat for example the stanchion of rear or stanchion rails to help eleviate that problem
In additon, max hp suggested on that boat is 8 hp only and this is based on experrience gentlemen due to my involvment with the boat and being the top dealer selling appx. 20 to 25% of that line.
crazy dave