Visit Great Wall during Beijing Capital Airport (PEK) layover, possible or no?

Hello, I am flying IAH -> PEK -> BKK
Flight lands PEK 04:50
Layover in PEK will be either
9hr 25 mins 04:50 to 14:15
Or 14hr 45 mins 04:50 to 19:35

Is it possible to get out into a taxi by 06:30 and to Mutianyu GW by 08:00. Then start return 10:30 arrive PEK by 12:00 and get through everything and to my gate by 13:30(ish) for the 14:15?
That time will be 1am for me and I'll be exhausted and just want to sleep on the flight to BKK. Previous trips I'm always napping 13:00 -> 17:00 so this is ideal.
Possible?
Anyone ever actually done this or know anyone who has left the airport on a layover? This works amazingly well in HK.
Thank you!