I have used a product from "Proform" i think it's called panel guard, it's tintable and tough.
I have used it as undercoat and has held up great.
What this guy suggested is the direction you need to go. The reason for this is because Chip guard painted over will only cause white spots when the rocks hit the outer layer of paint. If you notice on alot of vehicles, when their chip guard has alot of chips in it from rocks, the under lying layer is usually white. Therefore I would suggest a chip guard that is either Tintable....or the bottom 2-3 inches going with a "two tone" like paint job. For example, the upper portion your color, the lower layer almost as if you have a rhino lining or something that is a solid color when it is sprayed. Or even the same color as you are painting the entire truck. So that when it does get chipped, it is still the same color as the exterior chip guard.
Simply put, get your paint job......take some tape and tape off the lower sections all the way around your truck, sand the portion down and throw a cover over the rest of the vehicle so nothing is exposed. Don't forget to cover the wheels as well. Then, get yourself a black truck coating, or a 2 part bed liner kit....something that is durable and spray it yourself.
Here is an example of an entire truck sprayed.....my 85 awhile back.
Now look at the lower portion after I painted the top half with rattle can.
Just keep in mind that the 2 part bedliner type product will fade and not have a glossy color. This will be the only downside to a bedliner type lower portion. But again, I think the guy I am quoting is going in the right direction.
