I have an '07, 170" wb extended. Before I put in my sleeper I had 15', 6" of cargo space. I measured 12' from the end and built the wall there, leaving me slightly over 40" for the sleeper. I attached a frame along the bulkhead wall and got a small mattress. The bed is 25" wide, which leaves me a little bit of space between the edge of the bed and the seats. I have storage under the bed and a couple cabinets between the bed and the seats. The one behind the driver's seat is only about as tall as the bed and holds my underwear and socks and also serves as a nightstand. The one behind the passenger seat is almost to the ceiling and has my printer/scanner/copier combo, portable DVD player, game system, DVDs, books, and extra beddings. I put a clothes rod between the top of that cabinet and the bulkhead wall and I hang my clothes there, so my clothes are hanging just above my feet while I'm sleeping. It's not a bad space.
About the extra revenue for three skids, I'm not sure how that would play out with another carrier. I utilize the space quite a bit because if I can't find a good expedite I'll combine LTLs. I get a fair amount of long loads over 8' long, but the bread and butter is still the one or two skids.