Seems like the last couple of planes have needed the battery to be installed in unusual places to avoid adding dead weight for balance. I have been wrapping the battery with thin closed cell packing foam and then wrapping that with clear shipping tape.
Using super goo or similar I then glue the battery where I want it to be.
In the event it needs to be removed the tape can be cut and the battery will come out easily enough.
The RX gets held in place using any of the methods described earlier in the thread.