So the bunk idea ive banged together is leaving me with about 120" of cargo. Is this gonna be adequate space or should i try for more? Im trying to make sure i dont run into any problems down the road with fitting cargo.
10' will more than do for most 2 pallet loads. 3 pallet loads @ 40 x 48 x whatever, will fit in the 120 inches 40 x 3 = 120, but what about securing the load... I would look at 3 x 48 = 144 plus a few inches to lock the straps. Also, without the extra space, you may have to ask about the dimensions of every load (Though dispatch should have your dims on file), if they say 3 pallets, and nobody asks, it could leave you in an odd situation...
I started out in an 06 Sprinter Extended model and ran my bed along the passenger side with the pillow area up by the glove box. All my tools, battery and things like that were under the bed.
Just a note: Depending on whether or not you will be logging "DOT", they have some minimums for sleeper areas. I'm not sure what they are (I haven't driven Big Trucks for a while, nor had to keep up with the reg's.) It's something to look into though.
Just my op-onion.