Now this is rocket science, Stirling engines are being considered to be used on some space missions to replace RTGs (Radio-isotopic Thermoelectric Generators).
They're more efficient than thermocouples at generating electricity, but produce a lot more vibration, which means that they aren't a good idea on something like an orbiting observatory, but are useful on manned spacecraft which already have a lot of vibration (from people!)
One place where NASA was considering using them was on a next generation version of the Lunar Rover, which would have had 6 wheels instead of 4, and could be driven remotely from Earth as a teleoperated device when not being driven around by an astronaut.
So, they would be a sensible choice for a camp fire powered generator, could one be built small and lightweight enough.
OT ramble: The original Lunar Rovers cost $38 million dollars to develop, and travelled just over 56 miles in total, so that works out at around $677000 per mile, which makes the running costs of my Corsa seem quite reasonable.