I wanted to put an AirTag on my XPeak, but there was nothing created yet. This is remixed from the original on Thingiverse by photof2as. They were awesome and put in the 3mf file that I was able to modify to make it fit the XPeak. The screws for the tail light on my XPeak are 50mm apart.

His original design had a tight fit for the AirTag, which I kept. It will fit in the hole, but you will have to push it. It will keep it from rattling around. 

When I first printed this, I kept mostly the same dimensions (40mm square section) and it was a tight fit for the nuts to go back on. This version that is uploaded has a 36mm square section. It should hopefully make the nuts easier to go on. I did not reprint, due to getting it on the first time and I don't want to spend the time trying to get it back off. (I had to turn the crescent wrench 1/8 of a turn, then flip it to turn another 1/8, then repeat)

Let me know if there are any issues.

I also included the 3mf and step files with the STL.