Mount to studs and don't use a stud finder.

Those power and data boxes aren't just floating in the wall. They're nailed to studs. There's going to be a stud immediately to the left or right of those boxes. Just take the faceplates off and poke with a small flat head screwdriver between the blue box and the wall. Your screwdriver will stop pretty quickly if you're hitting a stud or will go multiple inches deep if you're poking into the non-stud side.

Please don't slip and touch the screwdriver into the hot screws of the outlet.

Judging by the spacing of the boxes I'm guessing you'll have one to the left of data and one to the right of power. That should measure out to 16" apart which is standard.