I think the stick on pad heaters are safe. They have been used for years on air cooled aircraft engines. We left them plugged in forever. Never-ever heard of a fire.

But, School of Hard Knocks, would you have enough ac power to plug in? If that pad draws 950 watts & you have a 1000 w block heater, you're almost at the capacity of a typical 20 amp ac circuit breaker, throwing in some loss for cord length. That's assuming absolutely nothing else is plugged to that circuit (not outlet, the circuit). Maybe your circuit would handle it fine though. You might want to check that out.