The Tacksman of Strond is distinguished by humanity to his Sub-Tenants and Scallags, who are objects of envy to all the other Subtenants and Scallags of Harris."
Travels in the Western Hebrides from 1782 to 1790
By the Rev. John Lane Buchanan Published 1793
I think Buchanan, who is relentlessly scathing in his comments regarding the Tacksman class, presents these two (neighbouring) extremes from Harris partly as a prescient warning of what happens when power is concentrated in the hands of one individual and his cronies and partly to demonstrate that the excesses of the Tacksmen generally were neither necessary nor inevitable.
I don't know who these two individuals were but we do know that Mrs Ann Campbell was the Tackswoman of Strond and Killigray at the turn of the 18th Century, and that she was similarly well-disposed to her Tenants & Cottars, so maybe she had inherited that position and it was Mr Campbell that Buchanan was referring to?
More commentary from this account, including an explanation of Buchanan's division of the people into Lairds, Tacksmen, Sub-Tenants & Scallags, can be read here.
The Gaelic for Tacksman is Gabhaltach whilst a Sub-Tenant is a Maladair. Scallag, which may or may not be the etymological root of 'Scallywag', does not appear to have a Gaelic equivalent but also occurs in the 1794 Statistical Account as can be seen here.