Very nice conversion! Well thought out interior design that is clean and neat. I was originally considering a box truck like yours, but fell in love with the school bus idea because of better ground clearance.
If you're looking for an idea for the paint, why settle on one design? With that much "canvas" you could do anything from modern graphics, to a landscape scenery (which I'm partial to), or even a mural depicting each area you've visited in your unique RV. Or... if you live in it for any length of time, you could put a bogus company on the side for camouflage. The possibilities are endless!