Unity engine Personal Edition is free, so what's the limitation for having users create their own maps which could then be loaded into FPV FR Recharged?
Of course, it takes quite some time to get the experience how things work in Units it seems:
Hi FPV Freerider,
As an experienced Unity Dev it is quite simple to add new scenes. All you need to do is request the level (in unity scene format), and then add it to your own by importing the scene. Unfortunately this doesn't allow you to add it in as dlc. You would need to compile a new executable