As said before, any good automotive paint shop can shoot your paint with their magic gun and match the paint. Can you take the water heater door to them? Last summer I replaced the two front fenders on a Ford pickup because of rust. Paint was two tone. Had what I called a metallic gray and white. Not common. Code sticker on door jam was missing from previous accident. They matched the paint perfectly even adding some fade to the gray. Hard to believe the technology.
When the stripping on the mh started to fade some years ago, I took it down to the paint store and had them use their magic gun to match the stripping colors. I painted right over the vinyl with excellent results. I also had them mix me up an aerosol can of each stripe color for touch up.