If by "mask" you mean a front end bra, I can give you my experience.
Purchased a bra for our coach in March, 2013. Delivery was fast, and the product is excellent. A high-quality bra is not cheap....and this one wasn't. But I am very pleased with it. It is made of heavy material, fits well, and the mounting instructions and hardware were very good. I did have to add a couple of snaps at the bottom corners of the bra to ensure a snug, good-looking fit down there on our coach. I also added velcro along the bottom edge of the bra and the corresponding bottom lip of the motor home valance panel to, again, ensure a smooth, wrinkle free fit. I admit, I am a bit of a "bug" on fit and finish. I also remove the bra from the coach when the coach is in storage for any length of time. I did not buy the bra so much to protect the front end of our coach, but rather to cover up some normal "road rash" and paint scratches, etc. that I grew weary of seeing. When installed, the bra looks awesome....IMO.
Re vehicle bras, some folks like 'em....some don't. I absolutely love the clean, "new" look it gives to our coach. I would add this suggestion, having had quality bras on quite a few vehicles over the years. One of the primary killers of a vehicle's paint finish beneath a bra is a loose, poorly-fittinging bra which allows accumulated grit and dirt under the bra to become sand paper as the bra moves and flaps around. Ugly. Also, an unclean coach surface combined with a dirty backside on the bra will have similiar results. Also ugly. One last thought. When possible, don't allow a wet bra to sit on the paint surface for an extended period of time, especially in the sun. Over time, this can "raise" the clearcoat and dull the paint below. Just my 2 cents....FWIW. Hope this is helpful.
2003 Fleetwood Revolution DP