if you carry , acetone , isopropyl , and low odor white spirit with u on the van ... those three will cover most inks , makeup etc along with just general detergent , if its not coming out with those three ... your probably screwwd .... after that your going bleaching and dyeing.
low odour white spirit ... B&q , homebase etc The other two ... small quantities in your local chemist ... but better value to buy a few 500mls from the likes of mistral chemicals .