i used a bunch of those style converters way back when, and they worked surprisingly well !
audiovox was the brand i used, so i can't say how other brands work. the one you show looks like a direct copy of the audiovox units.
fabbing a bracket for that should be as easy as a couple of 1/2 or 3/4" pieces of say, 18-20ga. angle and drilling a couple of small holes.
if you don't have the screws [probably metric] that bolts the bracket[s] to the unit, be very careful of the length you use, so as to not touch anything inside the case. those screws were super short for a reason.
please let us know how it preforms when you get it installed.