I did mine with a heat gun and fishing line, took them off no problem. I got the sticky adhesive off with.......WD40 (it works a charm, try it!!)
But yes, you will get the outlines of the letters left on your paint. Either heavy cut & polish as some have, OR just have that section of your boot resprayed, which i did & you'd never had even guessed they were there.
On a side note, that bug & tar remover stuff did not do much when i tried it lol