A .22, 35.5gr slug still has plenty of heat @ that distance. As others mentioned getting closer is always better but not to close you give yourself away.
Honestly at 175 it wouldn’t be an airgun at all. I know they are capable and at 100 or less my Gauntlet in 25 would be okay as long as I do my job but I would go for a .17hmr rimfire to be absolutely sure. BTDT in a similar situation.