mountain board hub size?

[AKA the A]

This may sound stupid, but does anyone have actual measurements of a hub for 8'' (200mm) mountainboard tires? I've searched high and low and can't find anything
(I'm interested in the outer diameters and width of the places where the hub meets the tire, don't care about the hole for the bearing...)

in case you're asking why - I'm thinking of DIYing a something like a Baja Board, but somewhat different...and definitely for a lot less then the $5k+VAT it sells here in EU
Normal MTB hubs won't work, since they're designed for a bearing in them...

Something like this:

 

[AKA the A]

So, since nobody could help, I simply ordered a cheapie 200x50mm tire with a rim and waited...for a month...gotta love Czech Post.
Turns out that the rim is a bit smaller and a lot narrower then I expected it to be, the inner tire rim is 95mm in diameter and 30mm wide. Developement continues...

The spokes are NOT the final version, as I still haven't decided on what to make this thing out of...
One posibility was 7075-T6 aluminium, but that would involve a lot of expensive machining (as you'd expect).
The other and ever increasingly more realistic variant is carbon fiber. For a part this small it will be cheaper even with the tooling costs. Now there's just the problem of having 0 experience with CF.
Anybody ever made a wheel of any kind out of CF? :|