Would it ok to bedliner the exposed areas of the frame?

[98EXPY 5-0]

By exposed, I mean visible from the outside of the truck.

I'd like to black out the frame where it is visible behind the wheels. I don't want to just paint them, because the stuff thrown up from the tires would eat it away really quick I would think. I was thinking spray or brush on bedliner, but I am concerned that it might trap moisture or in some other way cause that area to start rusting. I figure behind the liner, I wouldn't notice rust until it was too late.

 

[tallsville]

i had a friend do it to his bronco a couple years ago. so far so good. as long as its dry before you put the stuff on you shouldn't be trapping any moisture in.

 

[Wile E Coyote]

I used a 2-part epoxy spray-on DIY bed liner on the exterior of my land cruiser for protection from 'arizona pinstripes' while out on the trails.
Having said that, I'd personally choose something like ZeroRust, Chassis Saver, POR-15, etc and back that up with yearly shots of Fluid Film or the rustproofer of your choice.