How do I get my home-popped popcorn to be as dry as bagged popcorn?
The problem is not water content but mouth feel, smartfood and skinny pop are coated with a fine powder which has a dry mouth feel. You can dry your popcorn as long as you like but you'll never get to the same place with it. 

You can replicate smartfood cheddar popcorn by tossing your corn with mac and cheese powder, I'd give it a try and see if you get where you want to go, if it still seems wet in comparison then some extra drying may be good.