De-natured alcohol
I just wipe down the surface with alcohol, let it dry a minute. Then warm up and apply the wing walk.
My most recent walks are in good shape as far as adhesion goes...showing a little wear in the middle due to use though. I found that the stuff from McMaster-Carr works very well too at a slightly lower cost per foot, albeit you need to cut it length...whoop-dee-doo.
I like the idea of roughing it up a little, but the area that requires the most attention is the edges and I would be concerned about roughing up uncovered surface. I have found the adhesion is very good to paint, just need to ensure no oils or contaminates on the surface to be adhered to. If you warm up the walk with a heat gun before you stick it down, it will be easier to get it well stuck, especially around the rivets.