Probably a LOT! As I posted we have a huge smoker trailer. HUGE I tell ya! It does come in very handy when we are vending at large events. But, we are now rehabbing our old utility trailer so we can haul some of our smaller smokers with us to not so huge events. I love convenience of the big trailer because of the tons of storage, sinks, freezer, etc. But some days less is definitely more.
It's a little bit smaller than mine - For a comp, I use about 80lbs of charcoal (2 x 40lb bags of lump from Cal Hardwood and RD $10 per bag) plus any wood for add'l smoke. You could also take that propane grill out and mount your SW up front for add'l capacity. Convert the sink to a 3 compartment and away you go!