When I did mine, I relief cut the lip every 2-3" or so, and even closer though the bend area; made way easier to "roll" up. After cutting and before bending, used primer and body undercoat spray on the exposed metal and behind the inner quarter. I used a cloth covered 2X4 as a bucking bar, and carefully body hammered the lip up. Don't get tired and do it, the buck bar will help minimize dents and warping from the rolling and tired=mistakes. After happy with the lip roll, I hit again with primer and undercoat spray. I don't drive mine in the winter, but I have zero rust issues here in northern Illinois.