Help me pick a frame?

All,

I’m working on making a street unicycle that is fairly tough. Here is what I am thinking of so far:

Sun Mammoth 26" Rim, Profile Hub & Cranks, Miyata Air Conversion.

I will probably start with a 26" x 2.0" IRC Duro Metro, but I want to be able to use fatter street tires, if anybody ever makes any. That is why I am going with the Mammoth.

So, what kind of frame should I get? I want to be able to, in theory, handle a 3.0"x2.6" tire with comfortable (or at least decent) side AND top clearance. Now I know that there aren’t any street tires that big now, but one day there may be.

Suggestions?

Lewis