I have one of the 'standard' cheapo kettles that I've had for years - used it to great effect driving to Spain ten years ago, then learnt how not to use it...
I tried using it, through the cigar lighter socket as normal, and blew the fuse as I didn't have the engine running. Those things do pull a fair bit of power so be careful if you're not sure on your cabling (mainly on additional 12v sockets).
As for the camping stoves, to be fair, the length of time it takes to boil enough water for a cuppa would outweigh the cons of stopping and using one, but each to their own
Hope that helps!