Hi Don 
The surname still occurs in the area
There aren't any in Coigach any more though (local phone book)and I think I know all the locals there.
Acckkk, I get used to thinking in the 19th century, yes today Coigach refers to the area "beyond the Big Rock", but anciently it included all down to the border of Lechmelm, including Ullapool, where Joan Michael is.
I know Wikipedia should not be used as a primary source, but I contributed the edit there, and so mostly quoting myself it reads;
Coigach (Scottish Gaelic: A' Chòigeach) today refers to the peninsula "beyond the big rock" north of Ullapool, in Wester Ross in the Northwest Highlands of Scotland. Anciently till changes in civil registration districts in 1857[1] the Barony also included Isle Martin, the lands down to Corrie beyond Ullapool, the various farms of Strathkanaird, and eastward including the Forest of Achall and Rhiddorach.
you also wrote;
Also, Badentarbet was cleared (according to the Cromartie Papers*) because the 'lady' didn't like
the fact that the tenants could see them from their houses so they were all moved to Tanera.
They may have temporarly been moved as a group to Tanera, but by 1851 here is disposition of the familys;
41-1 MacKenzies to Dornie
41-2 Morrisons to Achnahaird
41-3 80 year old Mary MacKenzie probably died, 40 year old Katherine MacLeod to unknown
41-4 Salmon fishers, transient
41-5 MacLeans, only family that remained
41-6 Mackenzie/Campbell to Tanera
41-7 MacLeans to Achnahaird
41-8 McRaes to Faochaig and Altandhu
41-9 McKenzie to Polbain
41-10 Campbell to Dornie
41-11 McLeod stayed at Badentarbat, unkown after 1851
41-12 McKenzie cannot trace, perhaps returned to Coast of Gruinard
41-13 McKenzie cannot trace
41-14 Macdonald to Polbain
All the best,
Donald.