Must, to some extent, disagree with your second paragraph above: in "The Scots Musical Museum", mainly published in the 1790s, the simple accompaniments made by Stephen Clarke (a "dropping bass", I think he called it) were said to be suitable for the guitar, though I can see that its form then might have been closer to those "other stringed instruments" you mention. I can't remember whether I got this from one of the volumes, or from one of Burns's letters about the collection.