I've use those plastic adhesive on mine & still no cracks or flaking after a few years later..just make sure you clean off the surface real good with cleaning solvent..alcohol, etc..& then spray a few coat of adhesive, then prime, paint & clearcoat...easy mod ever..

 

I must say I'm super impressed with automotivetouchup.com's products. Not only does the paint match great and the clear coat is of nice quality, but the spraying tip, sprays a real fine mist from both in a fan like direction. Made this DIY very easy. No runs at all and with very consist/equal spraying. The clear coat is drying as I type. Since I manage a lowes here, I bought the plastic adhesive and automotive primer there. Those were more of a challenge to use with the old school spraying tip. The spray doesn't fan out like the paint and clear. So for those thinking about doing this, use their products to make the job so much easier. It was delivered in four days after order was placed. And pricing is very reasonable.