(update latest event, buddy seat backside job)
After one and a half month of looking all over the world for Vinylspray aerosols, I finally found them. Not without problems again of course.
When we taped the first section and sprayed it orange, it came of the next day. Had to tell the store the whole story and redo the whole process of cleaning, grinding, taping and spraying.
After two days of taping each color and wrapping up the rest of the seat for protection - this is the result.
The blue color was mixed until it was about the same color of the blue used on the hood. I gambled the orange color on an existing RAL color and black was easy. It looks perfect.
Praying that it will last for a very long time, it should be able to hold when you sit on it but this seems to be another sort of vinylspray, so no more passengers and bags.