Very interesting road this. Be warned, it is single track, but if you like scenery combos of water & hills then its worth it. The views across to Arran are superb, especially on a clear day. Almost no traffic, but the bends need care since its a single track road.
Not much in Campbeltown, but a good loop is down the east coast from Tarbert to Campbeltown, and blast up the main road on the west. Its my fave part of Scotland.
Slower but much more interesting road from Tarbert via Kennacraig then down to Carradale then to Campbelltown. Single track with passing places and some tricky bends to negotiate - sharp, twisty and steep. Looking over Kilbrannan Sound to Arran is georgeous and high road position gives great view. Summer ferry to Lochranza on Arran leaves from Claonaig short distance after start of this route. Great campsite at Carradale but try to keep this a secret.