What I did, is on the back side, the side with out the marks on it. I used a fine file to flatten about 75% of the face. Then I sanded it down just like you would do with paint. But worked though the grades until the final sand was done with 4 micron "grit". Same process I use to prep all my metal under the hood for polish. But I did not polish the dip. It leaves a smooth flat surface just like most dips are.
I originally tried scuffing the surface, but that was just as hard to read.
Also, to double check the stick, I use a "fish", basically a long flat flexible piece of metal, just like a normal dip stick, just more flexible (works very well).