Joystick calibration - there doesn't seem to be one, what can you do to workaround?

I'm working on a FPV Quad flying simulator. The idea here being that existing RC pilots can plug in their existing RC radios and fly that way (here's a intro to it on my YouTube channel if you want to get the idea https://youtu.be/QgaB_8Gc1Cc )

I developed this on a Mac and tested using a few different radios that plug in via USB and their sticks seemed to work well going nicely through the -1 to +1 with 0 bang in the centre. I did test on a Windows machine and didn't have an issue. However, now that other people have access to it there has been lots of people failing to be able to get their joysticks to do what they expect. We've got things like sticks looping around when the max point hits at the centre of the physical stick. Whilst I could create my own calibration if the sticks merely didn't go the whole range, it seems impossible to do anything about sticks that have too much range and thus loop around.

I should point out that although that although these radios seem a bit weird and wonderful as far as a normal input device goes, people are telling me that they look fine under the regular windows calibration and the sticks act normally.

With no option to calibrate a stick in Unity, what can I do to all the users that are stuck ?