For a bike application, it would make since to just coat the bottom of the downtube, and/or, the backside of the seat tube. If/when I get my truck bed lined, I've thought about masking off the bike for them to coat those areas. I heard Rhino liner keeps an elastic property after its dry.
I joke about coating my entire truck. Wouldn't worry that much about people keying the truck, or opening their door either. as I said I keed, I keeed.