Wheels-Tires Tire fitment: Maximizing tire. How much clearance for sway?

These will be track tires. It'll be 28" tall, and wheel width is looking to be 12.33".

This is the tire I'm currently considering:

Tire size: 28.0/11.5-15
measured wheel: 10 (but MT recommends that tread width is within +/- 1" of wheel width, and I'm just outside of this)
Height: 28
Section width: 12.9 (but MT says add 0.4 for every extra inch. In this case, 2.33*.4 = .932. So, Section width might be 13.832")
Tread width: 11.0
Circuference: 88
Compound: M5
Suggested Tube: 90000000290
Weight: 26
MATL#: 90000000856
Part #: 3057

But, I guess I have my answer right there. If my wheel well measures about 15" from fender lip to tub on each side, then I have less than 0.6" on each side even with perfect back spacing. I think that's just too close for comfort.

Alright, after a bunch of measuring, calculating, guessing and himhawing, I've come up with a best guess:

10x11.33 wheel with 6.5" BS.
Then the Mickey Thompson 28.0/10.5-15W stiff wall. It has a 10.9" tread width, a section width, including adjustment for wider rim, of 13.6.

This will leave me with a slightly conservative estimate of 3/4" clearance to the tub and if rolling the fender lip gives me just 1/4" extra, I'll have more than 1/2" clearance to the fender lip. I suspect that the stiff wall tires have less sway, which should help. MT also says on a wider wheel and with tubes, it further reduces sway and stiffens the sidewall.

So, I'll sleep on it, and then probably pull the trigger in the next week.

Now, what do I need/want up front? What width rim and tire for a skinny? Does stiff wall out back make any difference on the choice of skinny tire?