First fires of this type (TV turned off) are rare, VERY VERY Rare, your laptop is a much greater danger.
Second.. Turning off everything not needed at the circuit breaker panel is not a bad idea.. In fact I think its a good idea.
Finally: IF the TV is going to flame on, or anyhthing else, Would you rather it happen, as it did to your friend, when the RIG is parked, vacant, in your yard, or in the middle of the night in the middle of a Camping trip when depending on just what flames on you might not wake up in time or even if you do the Rig is destroyed and your trip toast.