Plenty of places to the west of Lochgilphead - thinking down the Knapdale area or towards Campbelltown. Some stony, some sandy. Plenty of opportunity for wild camping.
North end of Macrihanish, not far from small carpark at Westport, camp at base of dunes where it's a bit more sheltered. Only 5 mins from Campbeltown shops and will probably be a few surfers tents there, nice drive up from Glasgow.
Was up there with my two boys on Thursday, great weather,silver sands, had the fun kayak in the water and a great wee cycle up to Glenfinnan Bothy on the way up. Coming back , thunder and lightning and torrential rain. Fantastic day though.