Pelican, went to the local go cart shop, they either had a very flash steering wheel, which would give me lap times and as a by product digital temp readings. They also had little digital temp displays with a metre of cable to the sender, which needed to be installed in the coolant system somewhere. these temp displays did not have an output for a screamer or adjustment for warning, so were of similar operation as the analogue temp guages.
I will try the web again and see if I can find something such as you mentioned.
Cheers
Steve