Great news!! My method of painting the sidepanels while keeping the side artwork on (masked) works.
I know that at least one of you is very interested in this method, so here is how I did it (part 2, see above for the first part, the masking).
After I masked the sideart, I applied one layer of primer (Histor supergrondverf). When it was dry, I noticed that it kind of ‘creeped up’ against the edges of the artwork. Because I was worried that this would effect the end result (no nice tight edges of the artwork), I took a very common and easy to guide tool to just peel off about 0.5 mm of primer around the edges of the artwork. The tool? My fingernails, sharp, but not too sharp to accidentally damage the artwork.


After that I sanded the sidepanel with sandpaper (400 correl) and water until it was as smooth as a baby’s bottom. Never sanded with water before, but boy, you get great results.
Then I applied the first coat of Nintendo blue. When it was dry I sanded it again, carefully. Then I applied a second coat. Just look how tight the paint is against the artwork (the white line is only there on the photo).

Yesterday evening the moment of truth was there. I couldn’t wait any longer, the artwork had to be unmasked again.







And here is the endresult. It’s beyond my expectation, you can’t see that the artwork never left the building. Uh, the cab I mean.There was no paint leakage on the artwork whatsoever, only a few spots of glue remains from the masking vinyl on the artwork, but this was very easy to remove (be careful with sticker remover, it also removes paint). And although the color of the sidepanel looks a bit off on the photos, it is in fact spot on (inside the cab there is an original blue part wjich I used to match the color).



I don’t know if anybody has done it before, but if you are patient and careful, and use the right tools, you can do it. Now I can start working on the other sidepanel (I already applied the first layer of blue paint this morning). Can you imagine how happy I am!