I would honestly look in to making a wall test kit, I have a 3M one but that won't really help you with Oracal, 3M gives you everything you need in it though pre packed, but cut a few diff. vinyl series into about 1inch rolls and stick them on, also to increase your surfaces acceptance to adhesive wipe twice with rubbing alcohol (70%). If door gets repainted and you'd like it to last as long as possible, wait 30 days, thats the proper time for paint to cure from out gassing, specially for interior paints. The wall test kit is mainly for interior wall paints but I think it'd be good to exercise for any painted areas because of the inconsistency of VOC levels in paint. There's a formula for knowing if the material will last, you need to leave it on there for 15 minutes and then peel off with a spring scale, you obviously don't want it to remove too easily.