I too wanted to color change the wagen some day, but it is
a lot of work! Plus, at least the brown you have is a nice shade reminding me of hot chocolate or coffee with cream, rather than the tans I keep seeing that are so dreary.
What I am going to do on the wagen when it comes time is two tone like the Service Wagens. However, don't think any of the colors you have offered would work. Mine is non-metallic white, so limits the second color to non-metallic also. Figured the forest green for the bottom go great with the white top and Palomino interior. Brown and white might, maybe even brown and grey, now I think more?