Don, Sorry to hear about the woes of your travel experience up this way. I feel your pain!
FWIW, this is not a new situation with fires in just the last couple of years. I've lived in Montana for over 40 years and yes there were always threats of fires and a few cropped up from time to time, probably the most famous being the Yellowstone fires of 1988 but even that was unusual in those days. I used to live here for the summers, certainly not the winters, having frost bitten my feet a couple of times with long cross country ski trips. Anymore summers are a season of dread, I'm dead serious about this. Air quality here in SW Montana is awful now although our fire season started considerably later than all of our neighboring states, mostly due to the extreme winter we had with heavy snow. But we get smoke from fires in other states as far away as CA, NV, OR and or WA and others. What I am getting to is we have been experiencing wide spread western fire seasons such as this for what has to be a decade ± a year or so by now, and doubt there will be much of an end to it anytime soon if ever.
I can understand those who want to come earlier (May & June), and you can certainly do that but understand there will still be lots of snow in the mountains meaning hiking becomes very difficult if not impossible unless you're an extremist. For active people you might end up with a windshield tour of the area rather than a true outdoor adventure unfortunately. Weather can also be highly unpredictable during these months too. Its not at all uncommon to experience 1-3 foot blizzards and snowstorms during April and May, (they are a given in Mar-Apr) here in Bozeman at just under a mile high. I have photographs to prove it too. But on a good year May and early June can be downright gorgeous with snow capped peaks and green grass and fields that defy the imagination. Just don't expect to bag too many peaks during this time. Lower elevation cycling is generally good however during this period, albeit a bit brisk and chilly at times. Come prepared.
Feel free to contact me directly for any future trips, be glad to provide an on the ground report. Hope this helps, but probably not too encouraging.