Here's how I installed mine. I used the slide bracket Skeeter is using for their boats which is made here in Texas by a company called R&R Design. They run $150 and are much stiffer and heavier duty than the MKA47. On top of that this bracket has a spring loaded pin that lets you go from front to back without having to screw a bolt like the MKA47.
I used a Motorguide aluminum quick release bracket also, and the good news is the Motorguide bracket bolts directly to the R&R Design bracket. The one problem I ran into was the "knuckles" were 1/8" too low and they were touching the bottom bracket when pulled all the way back. Went to Home Depot and got a flat aluminum piece of stock that was 1/8" thick and installed it between the R&R and Motorguide brackets. Done!!
After all this, guess what? I went to put the propeller on the motor and the minute I spun it with my hand I could tell something was wrong. Sounds like a piece of the magnets or armature has come apart inside.
Sounds like this...
https://www.youtube.com/watch?v=Az_BVR9__3M
I think I have a Harley now.