Think I may have replied to your query earlier. Campsites at Point Sands (mile north of Tayinloan: Kintyre Way passes through the site) Carradale, Machrihanish and Southend. Between Tarbert and Claonaig you can camp on the foreshore or in the rough grazing on the other side of the road: it seems to be an accepted thing. I live in the area and I also operate Tayinloan Taxi and Baggage Transfers. If I can help at all with local information, just ask.
If you want to know about buses from Glasgow,
www.citylink.co.uk operate services 4 each way daily, except Sunday 3 each way. Flights with BA from Glasgow International direct to Campbeltown around 09.00hrs and 16.30 hrs daily except Saturday and Sunday.
Any other questions, just ask.
All the best
Brian Shepherd