I remixed this from a similar part I found that was designed to hold the Team BlackSheep Unify Pro. The Unify Pro HV is a little bigger. While I was at it, I also made my design parametric so I could make the exact same thing for the smaller Unify Pro, as well as for the Team BlackSheep CrossFire Micro Receiver.

Since they are all flat on the bottom, you could mount the receiver and one of the video transmitters back-to-back on 6mm standoffs above your board. One will be facing toward the board, the other will be facing up. You can also mount them 90º to each other so there isn't a conflict between connectors and antennas.

The holders are deliberately sized so that they aren't quite tall enough for the boards. This way, the flexibility of the TPU will hold them nice and snug, and still allow them to mount nicely on your standoffs. Pictures are of the Unify Pro HV mount since that's all I had at the time, but the other mounts have been tested and work the same way.