The "transfer case - conventional axle" arrangement requires the axle/diff to be inverted (because the pinion is now faced rearwards). That will take some thinking regarding lubrication and drainback. Note that transfer cases (either idler geared or chain drive) will need some cooling help (part of the reason the owners manuals have a recommended top speed in 4WD-Hi range).
I know many of the chain drive type units have a gear oil pump, so it should be possible to add radiator w/ fan. After visiting with Kent R., I need to learn more about those pumps and how to cool off a chain! I suspect part of the advantage of Hi Vo is the ability to give up heat (it is even used in aircraft powertrains, using engine oil pressure as the cooling spray, in an enclosed drive).
After reading the previous posts, I realized why the boat V-drives might be good...since boats are "always going uphill, and never coast" at anything above trolling speed! They must have some pretty good bits in those things...I don't know anything about them, myself.
We sure are a group for "trying to build a better mousetrap", aren't we!
Regards, JimL