I know it sounds like the back side of the world but taking Purchase Parkway south to 51 to 155 to I-55 north is lots of times a better option, especially if you are hunting south of Portageville.
Sorry for your luck.
Another word of caution----Posted speed limit thru Cairo is just that. I've seen them write tickets to KY vehicles for 2 mph over the speed limit. IMO, they should have blown up Cairo then let it flood a couple years back instead of flooding 160,000 acres of prime farm land when they blew the levees on the Mississippi.