I lived in a mobile at one time so I know what you mean.
We got extra storage in the bath with an over the toilet storage unit.
There is a primer you can buy that goes right over wallpaper. I think it seals it so the paper won't peel. I'm sure you can find that information at your local paint store.
There is a filler you use that fills the groves in the paneling if you want to. You also can paint right over the panel.
I had a white kitchen and used decoration for punch that blended it in with the living area. It made the kitchen look bigger. I painted the living area a green/blue 3 walls. On one side wall I painted it one shade lighter by adding white paint. It gave the illusion of a larger room. The bedrooms were a tan/beige with white trim and a gold carpet. Now I wall-papered and end and a sidewall in the master bedroom with a textured, just a hint of color wallpaper. It had a great effect.
You don't have to spend a lot $$, just do the best detailing that you can. I hope I gave you some ideas, good luck with your project.