rwm,
Everything that you said is extremely valid.
A possible, or partial, solution may be to combine the power train, rotor hubs and flight controls in a single compact package. This 'package' might be certified. The homebuilder then attaches to it a fuselage, landing gear, blades and engine. This concept is being considered at
Dragonfly
Coincidentally, Dennis Fetters, of Mini 500 fame, has reappeared and started posting on rec.aviation.hombuilt about a week ago. There are many posts and they get quite nasty.
No, I'd never heard of the parasol wing before.
Here's one, but at Mach 4.5 it might not comply with the Ultralight regulations 
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vorticey,
" head plane = hub plane"
hub plane = mast plane = shaft plane.
This plane is normal to the mast.
"the tip path plane on a teetering head never becomes unparrallel to the head plane"
You may be confusing the parts of a teetering rotor hub. A basic teetering hub is comprised of a mast head (hub) and a yoke. This head is firmly attached to the mast and therefor its only motion is that of rotation. The teetering hinge couples the head (hub) to the yoke. The yoke rotates with the hub and it also teeters with the blades.
When you refer to the 'head plane' you may be thinking in terms of the yoke and not the mast head.