I have friends with ones like these and they love them
For the next try: there are relatively cheap remote BBQ thermometers use this to juggle with the temperatures of your oven, probably better having the door a bit open (use some wooden spoon or something to hold it up).
More easy method: use a pressure cooker. The model on the image is more or less exakt 110degrees C on level one. You can decarb almost perfect by putting everything in a vacuum pack or a canning jar in 90 minutes.