Is there a way to adjust hot spots in a horizontal smoker setup?
Basically, what you need to do is create a baffle that distributes the smoke further into the main chamber. 

Checkout the mod #3 in this PDF for a CharGriller Smokin' Pro modification. 

http://www.deejayssmokepit.net/Downloads_files/CharGrilleMods.pdf

You can do this same thing with tin foil if you're on the low budget plan.