I come from Ohio (slightly more than 300 miles), and always get a walk-in permit. If you haven't had any AMS issues to date, I wouldn't worry about Diamox, although everyone is different, and on occasion, it is possible that someone who has had no issues with AMS so far could randomly have an issue with it; but that's probably more the exception than the rule. In November, weather will likely be your main concern. Some years, there is no snow until very late in the year, although that is also probably the exception. The store is closed that late, but the "portal" (meaning the trailhead area itself) is always "open", although if the weather doesn't cooperate, the road leading up to the portal may be closed by then, which means you would have to walk up to the portal before even beginning your hike at the trailhead.

CaT

If future generations are to remember us with gratitude rather than contempt, we must leave them more than the miracle of technology. We must leave them a glimpse of the world as it was in the beginning, not just after we got through with it.
- Lyndon Johnson, on signing the Wilderness Act into law (1964)