Two possibilities.
They/he may be at Pearl River Resort Casinos in Choctaw. Or they/he may be at any of the many casinos on the coast.
With Pearl being east of I-55, and with him heading east, he's either in the eastern part of the state (Meridian) or the southern part of the state. From Pearl, he could be in Hattiesburg, Meridian, or Biloxi, or, like you said, mswriter, Alabama.
Then there's Louisiana...New Orleans is only a hop, skip, jump from Biloxi.
I really really doubt that he's still with her. If he left Vicksburg with her, then the roads between Vicksburg and Jackson are so rural.... she could be anywhere. And Vicksburg is on the Mississippi River, too. Not good for her.
She is such a remarkable looking woman that, if she's with him, someone will see her.