I use non-skid adhesive-backed strips that are a foot long X inch wide, these are available at home supply stores and used to improve safety on stairs.

I placed them on the raised ribs of my running boards where my feet always step in and out of the truck, work great, can hardly see them.

~ Cosmo
1949 Chevy Half Ton
Rocinante, like Don Quixote, he is awkward, past his prime, and engaged in a task beyond his capacities.
"...my good horse Rocinante, mine eternal and inseparable companion in all my journeys and courses." ...Don Quixote, Cervantes
"If you come to a fork in the road, take it."...Yogi Berra
"Rudeness is the weak man's imitation of strength." ...Eric Hoffer