I added an LED reading light in my slide out so I had the same problem of making a neat installation. I used a cord cover stuck to the wall. You can get it at any building products store such as Lowe's. It generally comes in a neutral ivory cover which might work for you. Otherwise you can paint it any color you want. It has a peal and stick backing so attachment is a snap. To get power to my light I taped into an enclosed adjacent cabinet that houses my water pump and converter. I found an unused output from the converter and wired it to a female "cigarette lighter" socket. I attached a male plug to the light. Now I can plug in the light when needed and disconnect it when I retract the slide.
Wherever you want to install your strip light, you can probably find 12 volts nearby and tap into it. Then cover the wire with a cord cover.
