Screen printing would probably be the best option, and should work on them, even though they're a couple years old.
Vinyls hold up to a lot of flexing, bending, folding on banners, that's what we used before large format printers. I don't know how vinyl receptive that material is, or how well it would hold up to actual impacts, or for how long. I wouldn't say it's 100% not possible, just not very probable considering the application, and possibly a material that may not be very vinyl receptive. The only way you'll ever know for sure is to work with the customer, and do some experimenting if they're down for it.