If you want to build a similar cart, for mine i built it to mirror closely the dimensions of the smoker so i could get a 60-65 inch standard grill cover and use it for the entire thing. so its pretty wide, and i had to use 6 casters to make it work otherwise the weight of the smoker bent the center boards on the base, i could probably have used 2x4's and avoided that, but i had a big pile of scrap wood from where i built my sister in law a crib, toddler bed, full size bed, and changing table/dresser for her newborn (I'm a woodworker) so i pretty much just built the cart from leftovers, its why i had the slats for around the propane tank, those are very thin and pretty much don't do anything but add looks. its a total of 60 inches wide x 44 inches tall.
The nice thing about this smoker is, if you need to spray something on the food inside it and you were thinking ahead when you put the food in it, you can just open the stock top vent and stick the tip of the spray bottle in it, so you don't have to open it to spray the food.
and for those that want to know the chimney is 2.5 inches dia, i ended up having to use a jigsaw with a metal blade to make the hole, a hole saw i got from home depot wouldn't do it, it just gave me a groove to work with. And i put the same RTV gasket maker under the chimney as i did around the door, more to give it a seal for water then anything else.