Clip-ons are great in theory, but not so great in practice.
Something along the lines of a Bering Optics Super Hogster is pretty handy and high quality, and you can still pull it off the AR rail to use as a scanner.
An added bonus to a thermal that could possibly serve as a reason to have your employer make the purchase or as a tax write-off is to use the scanner during calving season to find a dumbazz two year old heifer's calf when she walks off and forgot where she left her calf. Or as a way to look at your buildings on a cold night to find areas of heat loss in need of extra insulation.