Staggered Wheels and Spare Tire Selection

[SkinnyX5]

I was thinking about some details concerning a staggered wheel set up as my next upgrade and come across an "issue" that I am not sure how to deal with.

For example, I intend to purchase style 214 rims where the width of the rear wheels are an inch wider than the fronts (20x11 vs. 20x10). Couple that with tires of different sizes (315/35/20 rears and 275/40/20 fronts). My question is how do you address the issue of which wheel set up do you carry as a spare in the case of a flat?

Do you take a gamble and choose a spare rear or front? Or do you reduce risks by mounting run flats that at least give you a 50-mile buffer to find a service station? Or, do you simply wait for the tow truck? Otherwise, carrying around a spare front AND rear wheel would seem impractical.

To the members who currently run a staggered setup, how do you all deal with this apparent drawback?