what ive done on my previous cars rocker covers is, sand down the writing till its polsihed up, then get a cloth and dip it in clean oil, and lightly go over the wirting.
make sure it only VERY light, so it doesnt run down the side etc.
then after painting, and drying, you can easily wipe the wirting down with a cloth dipped in turps etc, but again, do it very lightly.
steve