I don't know "best" but going north to Saratoga, then to Laramie via the pass east of King's Canyon, then down the Front Range would work - staying clear of the fire TFRs and the plumes. Haven't checked to see if the TFRs are in that area, but you could detour north and east until you're clear.
And while your own personal tolerance might preclude this, you can go above 12,500' to up to 14,000' for 30 minutes without oxygen, and that gives you more options, for example, Grand Junction, Gunnison and Salida.
Dave