Iksars can indeed fix the Rivervale Cleric guild faction, My Iksar is loved all over Rivervale and can travel in and out with no issues
You will need to get Wolf form, which is pretty easy to get in Rivervale and do the following quest:
https://wiki.project1999.com/Cleric_Supplies
Been a couple years since I did this, I want to say it takes 20-30 turn ins to reach Dubious