Correct, if you don't have the inserts under the door skin for the bolts, it won't be pretty. The swingout-style mirrors add quite a bit of leverage, even though they are not heavy, they will still rip out the skin. I agree that it's a pain to fab up some kind of support, so stock doors with the mounting holes you want would be the best. Even the stock inserts can strip out, and the mirrors are flopping around. Guess the ? is what style are you looking to install?