Universal Controllers (Sensored and Sensorless) just need to have the Hall connector unplugged in order to switch to Sensorless mode.
If your Controller can't do that out of the Box, then it's not a universal Controller.
You can check Aliexpress for Sensorless or universal Controllers:
https://www.aliexpress.com/wholesale?ca ... controller
Just find a 48V Controller with about 30A and a documentation of what all the connectors do on the Controller.