This is by no means a personal recommendation but at the Chevrolet-
Toyota dealership where I work we use a Tech brand repair system
wherebye the tire is dismounted, the inner carcass is prepped and
buffed and a large "mushroom" patch-plug is applied from the inside
along with a special sealant.
We have never had an issue with these as it is impossible for the patch
to come loose. Of course I would never plug a tire tread close to the sidewall.
Check dealers in your area.
http://www.techtirerepairs.com/