Crazy? Probably, but I had an old dog of a sail that wouldn't withstand stitching and needed something. I tested some paints on test panels, chose one of the best, and ...
... after three a seasons it's still looking good, no pealing.
This is an inflatable paint I have used before (MDR Amazon Inflatable Boat Paint), so I'm not expecting any trouble. It seems to stretch with the cloth and I know it can handle the sun. Would I spec a new sail that way? Undecided.
A full report will be in Practical Sailor next year.