The only problem is that its been 17 years now. A lot of people have tried to find Lyle by way of identifying his ethnicity. So far, no cigar.
It's very possible that Lyle was from one of these tribes, but why then did no one from any of the reservations report a young man from their tribe as missing?
Below is a link to 970 missing person's reports that have been ruled out as not being Lyle. And I'm sure there are even more. If someone was looking for this guy, I have to think that one of the many who have been trying to make the match, over the last 17 years, would have found it by now.
https://docs.google.com/spreadsheets/d/1fat50H8N_Yn-Ndqh80FLP3YzK_-JCT70LgxsfU6jYUY/edit#gid=0
If you google the name Lyle Stevik about 20 pages of search options pop up.
After 17 years, the big new clue on this case may be what hasn't been found. And I think it may now be safe to assume that no one has been actively looking for this guy.
Side note on similar case Grateful Doe/ Jason Callahan:
Even though no one was actively looking for Callahan either, but once Jason Callahan's picture hit the internet, someone did come forward. And though I think people have been looking for Callahan for almost a decade, it was the crowdsourcing that finally culled out the right identity. And once his picture got out there, I believe his identity was discovered pretty quickly.
Lyle's picture, and story, has been out there for almost two decades now and nothing.