My 3 x great-grandfather, John Smart, also farmed at the Stoop according to the censuses for 1841 to 1861. He was born in Torthorwald, Dumfries in 1783, although he moved to Hamilton, Lanarkshire, when he married (in 1807). Sometime before 1839, he and his family moved to Stoop. By the 1871 census, John appears to have become well established in the Stoop area as he is described as a landowner, living at Lochmaben Road, Dumfries.
John Smart dies of old age in 1874 at the home of his granddaughter, Elizabeth Tait (nee Smith), on the Clonyard of Southwick farm, Kirkcudbrightshire. His will, proved in 1874, states that his personal estate includes: "Proportion of unpaid rents of property at Stoop of which [he] is Liferenter under the settlement of the late Miss Mary Carson of Stoop, still in the hands of her trustees under deduction of taxes."
I have yet to fathom who Mary Carson is, but she must have had a significant influence on the family as John Smart's eldest daughter (my 2 x great-grandmother), is named Mary Carson Smart. Could this Mary Carson be one of the area's major landowners that you're looking for? According to the 1895 Valuation Roll, John Smart's grandson (and my first cousin, 3 times removed), John Thomas Wingfield Smart (1862-1949), owns and lets out five houses, plus a garden and sundry land, in Victoria Place, Stoop. This is in addition to renting and occupying his family home at 65 English Street, Dumfries, and his joiner's workshop at Catherine Street, Dumfries.