I would think that a 2 part product would be fairly durable. I've considered coating just the raised rib areas. Yes it would take a while to mask off. I imagine it helps with the wet shoe slipping problem.

 

Definitely experiment with anything applied with a Shutz gun. I have used maybe three different Upol products and all of them could be adjusted with air pressure, distance from gun to panel. I almost always ended up thinning the product a bit to dial it in so it would lay down like I wanted it to. Raptor is thinned with any urethane based reducer. You'll need it to clean up anyway. Rattle can Raptor has to be thinned considerably already. Body Shutz gun applied products are always thick in my experience. I've probably had my Shutz gun 30 years and I remember using it the first time applying some chip guard on the rocker panels of an old 70s Chevy. It looked hideous. Truly like stucco.

 

I sprayed the outer sides of my inner fender panels with Raptor using a Devilbiss Finishline FLG gun with a 2.2 tip. I thinned the Raptor as per recommendations. The Raptor sprayed with a relatively fine spray and cured to a finish that was about the texture of 80 grit sandpaper. Excellent bond and build, I would use this technique again should I be looking for a finer texture coating.

 

I had mine done by a local place that sprays bedliner, don;t recall the brand, but they have held up well for 20 years.