All companies bas their fit on different lasts or foot shapes. Unfortunately, Keens may not work for you no matter what model.

Do you still have the Targhee's? If you do, you will find if you compress the heel on the shoe to make it narrower works and also on the Targhee there is a heel strap that will tighten the heel. How you use it is to tighten the laces more than you normally do until the shoe breaks in.
This tends to solve the heel slip problem in one or two times of wearing it.

Jerry