Seems like the last couple of Vans 'signature pants' have just been whatever pants they wanted to release anyway, and then they just slapped a pro's name on them. Both Gilbert and Justin Henry wear pretty distinctive pants normally, and their Vans pants don't really capture that - they both got just kind of boring beige pants.
Gilbert's regular pants aren't for me, but if I were making a 'Gilbert Crockett signature pant,' they probably wouldn't be just straight leg beige jeans. They could easily do loose/straight raw non-selvedge denim with some small signature details on the tags or buttons. Make them fit like a slightly toned down version of his regular jeans. The Cee Blues jeans are like $300, made in USA, selvedge denim, etc., so I don't think a mass produced $70 Vans imitation would cut into their sales on those.
The Justin Henry signature pants should probably be more along the lines of those cords that Quasi put out recently - loose up top, tapered, maybe slightly cropped, and in some kind of bold colour/fabric. Kids that want to dress like Justin Henry aren't looking for khakis.