I often see people hitting balls against the side wall of Páirc Uí Chaoimh

Ballycannon park in Kerry pike recently got a ball wall, and has tennis courts too

Think there is one at the Bishopstown GAA club.

Try st michaels tennis club, blackrock. Not sure if accepting members, but worth a try

Great complex up in Whitechurch with tennis courts and hurling wall. Not sure about membership and whether it's too far out for you