First of, welcome to the forums! ^^ I'm Catgirl Rin Rin AKA Victoria! Nice to meetcha, Zappa-Chan!
Naruto! Woo! I've never seen it but have heard great things about it. Hehe, it should be fine to wear tighter green jeans, as long as you are comfortable. There aren't many rules while cosplaying, although there are some no nudity or uncapped weapons and such ^^;
But yes! If you are comfy, that's great! If some people, with closed minds, see it as "Uncool", let them think that. I think it's great if you altered it your way to suit how you feel about it.
*Gives you pie* Go you! \^_^/