Hi
Ref the KK cook set - all good points : it is a bit of a faff cooking on it.
But if you use larger wood to burn than usual, it will obv burn for longer. Also, feed it in thru the air hole in the base, so you aren't moving the pot on and off all the time. And ensure the hole isn't facing the wind, to slow air flow / burn down.
And although you shouldn't run them empty, you can let them continually boil while cooking (as far as I know) - so there will be plenty of water for washing up and an after pan of bean cuppa
They are def not perfect, but cheap, fit in the KK bag & can be handy for basic cooking.
Cheers
Matt