You should have something like 12k of cargo capacity depending on what drive train and whats in the sleeper. It should be more for the smaller sleeper.
Mine comes in at 22k loaded (fuel, fat driver, supplies, etc...), with a reefer box and equipment (lift gate, ect ...) - leaving me with about 10k if I push it. I have 9800 on the truck a couple times but didn't like it.
The reefer box adds 1200lbs to a normal box (mines 16 feet but I figured to replace it with an 18 foot box), the reefer unit is another 950, the lift gate is 800 lbs - so 2950 roughly extra weight. So if I went to the 18 foot box, I would shed about 3000, which puts me at 13k capacity.