any of the trails in the central or eastern highlands will be far less popular, and far more ameanable for bushcrafty-type adventures - if you want Scotland, then they would be my choice.
heading right over to the west coast is also a good option - its very remote, its easy to find a discrete pitch, fishing etc.. is easy, and theres woodland right down to the waters edge in many places. however, if you want to cover a decent distance it can be something of a mare - by definition the coast is an endless stretch of headlands and inlets, and you might walk 20 miles along the coast and be 5 miles as the crow flies from where you started, and its also up-down-up-down-up-down-up-down-up-down - its knackering....
you pays your money and you takes your choice...
if you really fancy the adventure feeling, i'd offer Knoydart - firstly you get the ferry from Mallaig... there is some infrastructure on the peninsular, one or two bunkhouses, a small shop in Inverie, and a couple of bothies, but thats about it - no roads, no streetlights...