Maybe a shirt could just be gloves that met at the shoulders to cover the front, and expose the back, and pants could be boots that come all the way up? Don't think "different than any human", rather think "a different way than any human"
By that I mean, think of what parts of society are going to be similar and different. What would they have come up with? Are they more primal, technological, aesthetic, philosophical, industrial, or something else? That would dictate what kind of thing they could use as clothing.
