Dansy,
Do you know where your CG is located? Is it much further behind 120mm? I would prefer to solve the CG issue without having to add weight if possible.One option I have is to move a 700mha LiFe RX battery (about 40gram) further back above the lower wing. This is currently mount just behind the motor. Makes it a bit more difficult to get to if it needs to be charged, but if it solves the CG issue I guess I can live with it.
I also had a reply from Roberto P and he can provide the same cage as he makes them. If relocating the RX doesn't resolve the issue I think I'll go with the lipo cage.
Thomas