Movable TV mount for Ikea Besta

Hello everyone,
I am currently struggling with the following problem:

For the Besta cabinet with the Främsta back panel, there is only one original TV mount, which is hooked into the rails. Unfortunately, this mount is neither rotatable nor tiltable.

However, I definitely need a rotatable and tiltable TV mount. Has anyone else had the same problem and successfully solved it?

I had already considered buying the Främsta mount and using only the mounting brackets for the rails to screw on a third-party mount. The question would be whether the two upper mounting brackets alone would be sufficient, or if I would definitely need the two lower ones as well.

Best regards,
Daniel

You will definitely also need the ones below. The question is whether the external bracket also has such large hole distances to be able to realize it that way. I have already thought about the problem and considered mounting the external bracket on the vertical supports of the Framsta bracket. The only thing I am not sure about is whether the Framsta rails can withstand it, as the forces on the rail increase with the distance of the TV to the wall (keyword lever).