This is for a clean install, not an in-place update. Everything seemed to work for the Windows Update version of the Anniversary Update although I didn't play around with it that much to confirm everything.
The main difference I found was that things did not install unless item 5 was done manually within Device Manager to Unknown Device with Hardware ID of MAT0021.
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Using a combination of the mk8 Windows 10 and mk7 Windows 8.1 drivers, I've managed to successfully install Windows 10 x64 onto my mk5 (CF-19A). Attached is a text file of the order of install and what drivers I've used (eg. Windows-supplied, mk8 Win10 or mk7 Win8.1)
Everything essential works as far as I can tell, tested the Dock Replicator ports, internal MC7700 aircard and Firewire ports, all ok. Except:
I don't have a camera or fingerprint reader so I'm not able to confirm those.
Because Panasonic customized the video driver (thus unable to install and Windows is using its own driver,) I'm running into the same issue as Win8.1 where I think I'm missing one 'extra' level of screen dimming before off... that level is pretty important if you're using the Toughbook at night.

Update: GPS Registry entry is required to activate COM3 for the internal GPS. Otherwise, COM3 does appear in Device Manager but GPS data is not recognized.