I want to go through with the peace treaty for the civil war, but I also want to be Thane of Windhelm and own the house. As far as I know, you can become thane either after the Stormcloaks have liberated Skyrim or after Ulfric is replaced by the new Jarl (i.e. after the Imperials crush the revolt). But if I do either of these things, I can't conclude a treaty. If I choose the peace treaty route, will Ulfric let me become Thane of Eastmarch afterwards?

the peace treaty is only temporary, you will either need to join the stormcloaks or replace him with the imperials.

Dang it, I was hoping to avoid choising sides... Oh well. Thanks for your help!