Hi Cees
Omega.com is a good source for pre-fab thermocouple related hardware, with the caveat that the voltages are very fickle with thermocouples. Sorry, I’m honestly not sure if that would alter the readings or not. I’m inclined to say it’s safe, given that extensions are fairly common. I would, though, advise to try and match the wire gauge as closely as possible, and test the readings before and after.
Also, Granger.com sells the “mini quick connect” plugs–male and female. That’s where I always purchase mine.
One thing I did want to point out, is that the Bluetherm Duo has a threaded “tripod type” hole mount on the back. It might be possible to find a magnetic base, with a threaded bolt that would match the Bluetherm duo, and attach it to a cooler spot on the roaster. Just a thought.
Danny