I would turn my thoughts to the sleeper area. I think the sprinter is too narrow for most to sleep side to side? (correct me if I am wrong).
A lot, for sure, but not most, probably. The Sprinter is 65 inches wide. If you are a man and are taller than 5' 9½", (69½") or a woman and are taller than 5' 4" (5' 3" in Canada, ha!), then you are literally above average. It's a 50-50 split above and below those averages, so the question becomes are more people above the average height of the North American male more or less likely to have a Sprinter? It could be that taller people are consciously or unconsciously drawn to a Sprinter because they can stand up in it. But the number of women in a Sprinter would certainly cancel that out.
I'm exactly average and I sleep on a 30" wide bunk, and sleep very comfortably with no issues despite being 4 inches taller than the width of the Sprinter. On the rare occasions I feel the need to "plank" while in the bunk, I'll have my head at one corner of the mattress and my feet at the diagonal corner, and there's plenty of room. If I were taller then I'd want a wider bunk in order to have that length from corner to corner.
The diagonal (D = √sqrt [x² + y²]) of a 65"x30" rectangle is 71.5 inches (71.5891). There's a pillow involved, and your head and feet aren't pointed to perfectly fit within those 71.5 inches, so you'll be giving up a few of those inches. But 30x65 seems to be about right for 5'10" or shorter.
For every inch taller, you need to go two inches wider on the bunk to add roughly one inch to the diagonal. A 32 inch wide bunk yields a 72.44998 diagonal, which is fine for someone 5' 11". If you're 6' 4" (76 inches) tall, tho, then you need a bunk that's 42 inches wide (77.388626 diagonal).
I say all this because all too often people who are taller than 65 inches immediately dismiss the possibility of sleeping on a crosswise bunk. It all depends on how wide you make it, and whether or not you have the room to make it as wide as necessary. No matter what, I can sleep while loaded, and do so without any effort on having to set up the bunk, same as in a truck. It's always there, always ready, loaded or not.
Oh, hey, here ya go. Here's a calculator that will quickly and easily calculate the area, perimeter and diagonal of any rectangle.
Area, Perimeter and Diagonal of a Rectangle - Geometry Calculator
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