No, it's not possible.
The bigger thing I'd worry about is that the Thalmor have a habit of winding up on everyone's bad side. The Thalmor have an embassy and a keep up north, a few agents scattered about (some giving minor quests), and some in the countryside that will attack you if messed with or even on sight. There are only a few named NPCs, including an advisor at the College of Winterhold, an emissary and socialite, and an inquisitor. You can, of course, enforce things like the ban on Talos worship and refuse to help some people going against them, but the Thalmor don't have a proper questline.
As for avoiding fighting them, it's a little inevitable (main/guild quest related):
You have to infiltrate the embassy as part of the main quest line. Sneaking is actually pretty difficult here. I might just be missing something, but my solution was to kill everyone. Sorry, Thalmor, but I think Talos is a pretty cool guy. As for Ancano, he doesn't turn out to be a nice guy, either. And certain quests just sometimes have you fighting Thalmor for reasons that aren't well explained at the time. Working with the Blades is both verboten by the White-Gold Concordat and required by the main quest.
The gist of the above is that you can invent your own reasons to explain a few clashes with your colleagues, but you might need pretty high Persuade (IRL).