But, I believe he is talking about "space claim" and that the Alaskan on the truck is smaller than necessary given the extended wheelbase.
I wouldn't say "smaller than necessary"...I'd say "smaller than possible".
Sure, with that chassis, a much larger camper is certainly "possible" - but is it "necessary"? I don't think so.
As I recall, Don built the truck to accommodate himself and a border collie. I don't recall any mention of a significant other, so for just one guy and a dog, I would think that a 10' Alaskan NCO would be all that is really "necessary".
Tennmogger travels all over in a 1300 series Mog with a (I think) 8' Alaskan NCO - AND a wife (and I seem to recall children as well), and that is apparently all that is "necessary" for them to have a bloody good time.
Bill Caid did the same thing, with just himself and his significant other, and decided it wasn't enough - so he built the Hi-Lo on the Mercedes 817 chassis.
Different strokes for different folks. Just because every available inch of space wasn't used, that doesn't mean that it was "wasted". It just means that it wasn't "necessary" to use every available inch of space.
I personally really like the layout of Don's truck, though I would have reversed the camper to put the door at the front and leave a 4' gap to the cab.
Then I'd've hung the bike and spare tire(s) off the back and used the gap between the camper and cab as a mudroom/crawlthrough/(possibly) shower area with a generator in a box low on the port side (on top of the deck, so no need to pressurize the compartment ala Unicat), with storage above that, and hung a gangplank/stairway on the starboard side.
EDIT: And there is certainly something to be said for not maxing out the GVWR of the chassis as well.
