This is looking in the front drivers side storage compartment. Look at the top: You can see clear through to the other compartment on the other side. (You can see the mounting plates for the front two seats--the bolts at the very top.) I'd estimate there is about 3 or 4 inches of clearance in there. Really not much room for anything and it may have a few issues: Probably gets pretty warm in there being behind the engine and above the trans.
Or, about three or four folding step ladders. Perhaps some Tiki torches, a three leg Dutch oven stand, a Lantern stand, camera tripods, brooms, mops, brushes, etc.
I'm surprised a salesman didn't emphatically point out that huge "feature". When I was shopping for a motorhome, (regardless of brand or model), they NEVER missed a single opportunity to point out pass-through storage, even if it was only big enough for a broom handle.