Here's a backpack for a Micro size camera (Caddx / RunCam Micro Sparrow) and VTX (Eachine TX526 or similar).
I have used double sided tape to secure the VTX, but it may pay to add a small cable tie around and through the strap cavity, as the heat from the VTX may soften the tape.
You can secure it to your model either with Velcro on the base or using a 20mm Velcro strap through the cavity and around your aircraft. EG a glider.
In most of my aircraft, I use a 3S battery and I connect the Backpack to the balance lead. But CHECK the voltage rating on the camera and VTX.
This project was created in AUTODESK 123D design and sliced using Cura.