I've used the mushroom headed plugs to repair a torn/cut sidewall on a motorbike tyre, then a big vulcanised stick on patch over the tops on them, inside the tyre wall, then put a tube in it and rode a further 800 km home, it was a s/h tyre from a motorcycle shop, they had none that would fit.
The ride was ok ... all be it, at a slightly reduced speed, but still all the camping gear and the wife on the back ..... the road was so hot between Wilcannia and Cobar, the rubber was coming off in balls under the rear mudguard on the 750 Norton Commando .... and this was back in the 1978 ..... I doubt I'd care to try it these days if it is as hot there as it is here at the moment.
T1 Terry