Do It Yourself Spray On Bed Liner Do It Yourself Spray In Bedliner Questions?

Do it yourself spray in bedliner questions? - do it yourself spray on bed liner

I do a little self-spray in the line out of bed and asks questions about the application. I would be over my head. What is the best way to get a straight line? I thought about using duct tape car paint green. Should I, as it should wait until it dries? I want to also spread the floor 6 inches or less all the way around the outside to protect my truck from stones. I saw a couple of places online. Those who experience it done? I also have new bumpers front and rear of my car and I asked myself beaten steel spray or need a manual? I usually spray or roll. I have a gun, the lower layer. Each input has to do with experience, someone had to-it-yourself stuff is very much appreciated.