I happen to be dealing with something similar and asked about curtain sided trailers recently. I didn't get much response on here, but I did find an interesting solution. I am not convinced "one shot" will hold up to every day usage of expanding and contracting of the curtains. 3M sells a special vinyl just for the application, it is 190 curtain sided vinyl. Information says it needs to be solvent screen printed and clear coated. It comes in 48" x 50 yards. Approximately $2k or $3k for the roll. I can't remember exactly. I called my local automotive paint supply and they carry a vinyl paint. Exactly what you are probably looking for. Can be custom color matched at no extra charge. Has UV inhibitors already built in and flex additive. Formulated for vinyl. Outdoor durable. It's what I'm going to use and costs about $60 per quart.