I have written a sensor host to try and make it even easier to write sensors. It's a very lightweight self-hosted website that treats sensors as plugins. You can take a look here at an early prototype: https://github.com/rossdargan/PRTG-Sensors , and the example of the type of code you would have to write to create a sensor https://github.com/rossdargan/PRTG-Sensors/blob/master/Sensors/TestSensor/TestSensor/TestSensor.cs
This all takes advantage of the sensor type "HTTP Data Advanced". Hopefully there will be a few people on here interested in helping out with it!
Ta
Ross