I use a piece of 3/8" SBR (Styrene Butadiene Rubber) about 9x6 to pad the trolling motor clamp to the boat. I find this greatly increases traction and reduces the amount of twists on the clamp needed to secure the motor.

This stuff is very similar to a tire, has great grip, and will allow the trolling motor clamp feet to bite into it while pressing very firmly into the boat.
 

Thanks for the tip Craig.  Where could I find a small piece of this 3/8" material?  I found big rolls at Home Depot but only need 9x6".  

Thanks,

Jim 

I ordered this off Amazon. Not sure they have a smaller piece, but I was able to cut it to size with a box cutter and patience. 

https://www.amazon.com/Styrene-Butadiene-Rubber-Backing-Thickness/dp/B00L8NXU00?ref_=fsclp_pl_dp_7

Most excellent outstanding tip, Craig. Thank you. I bought a sheet of this on Amazon for just a bit over $15. It took me about 2 minutes to measure it, mark it with a BLUE Sharpie, and cut it with a sabre saw. I cut two pieces and mounted them on both sides of the front mounting plate on my Bass Baby. I have enough left for two more pieces, and will be glad to give them to any member. Just PM me and we'll set up to meet.

Perfect Craig, Just ordered.  I have a 40 lb foot control on front of my 17ft, and for fighting the frequent wind, I have also been mounting my 55 lb hand control on the back transom and letting my son operate when more thrust is required.  Because of the aluminum powder paint coating being too slippery to hold, the shaft usually kicks up when we turn sideways no matter how tight the screws. Nearly lost the motor twice. Plus it scratches the paint. I tried blocks of plywood, a sheet of sandpaper, nothing worked. I was about ready to screw-mount a wood plate with routered slots for the clamp feet, but did not really want to drill into my transom.  Hopefully your solution will fix this.

Thanks again.    

I've used this for about a dozen outings, and the only thing I've noticed is that as the day gets warmer and the rubber warms up, you may have to give it another half twist to tighten it back down.