Are there any tours that will allow an early morning tour on Thursday, September 28?
Hmmm, I only looked at the guide I know of, Pat Shelley who is excellent. He looks like he's booked on the 28 but has availability on 27 and 29.
http://www.tours-stonehenge.co.uk/inner-circle-tour-calendar.htm
You can book the Stone Circle Experience online yourself; it's not essential to have a "tour guide," although I do not know about availability that day. Check the calendar at
https://www.english-heritage.org.uk/visit/places/stonehenge/things-to-do/stone-circle-access-visits/
We did this Experience early morning one month ago (booked 5 months ahead and got the last two spots...) It was absolutely indescribable. I highly recommend it and would do it again in a heartbeat.
I am able to get a ticket for Sep 28 via Viator site. Pick up is at the Millennium Gloucester Hotel and cost is prohibitive. Where can I stay the night before at a reasonable rate? Maybe Air BnB and a taxi in the Am?
Just get the train to Salisbury and stay overnight there. You should be able to arrange an early morning taxi from there.
It's not clear to me what you would consider a reasonable rate... But, I highly recommend the Holiday Inn Amesbury (or maybe it's called Holiday Inn Amesbury/Stonehenge). It is less than 15 minutes' drive from Stonehenge Visitor Centre. I do not know if you can get a taxi from there, but the staff were so incredibly helpful to us that I would guess they would try to arrange it for you if you give them sufficient time to do so.
The restaurant there at the hotel is great too--we did both late supper and buffet breakfast, and I thought both meals were superb (convenient, although not inexpensive). The staff throughout really were a highlight of this place, though--very friendly and super helpful.