I'm in agreement with you about Jones County MS. However, I don't see a correlational between support for Bell-Everett and being an unconditional Unionist. Many Alabamians who later led Confederate commands signed petitions and led meetings in favor of the Constitutional Union Party. Future Confederate captain William H. Fowler proudly cited Henry CLay's motto, "The Union - It Must Be Preserved" in the masthead of his Tuscaloosa newspaper.
On the other hand, many dyed-in-the-wool Democrats who supported Breckinridge-Lane opposed secession and went over to the Yankees at their earliest opportunity. You need look no further than the Democratic stronghold of Winston County AL.