My client wants her new 16 ft. wheelchair ramp painted (not stained) to match her current house trim. I'm thinking to use the HD paint with slip additive. Do I have to put primer on the wood before painting it? (Please, say "no"!) The ramp is about 6 months old, so the wood is dry and in good shape. I don't have a paint sprayer, so it's going to be a pretty big job. Thanks for any advice or suggestions!