Owen Sheppeard kicked off the Blues' scoring with a fourth minute try and by half time the hosts had bagged a bonus point courtesy of further tries from darren Harris and Richard Lovering (2).
Campbell completed his try hat trick with a pair after the interval with Ellis Jenkins and Matt Roberts completing the rout.
Lewis Williams kicked two conversions and Josef Griffin four.
The Blues South under 16s defeated Gogledd Cymru 33-15 at Rumney with a bonus point to boot.
Gareth Thompson, Luke O'Brien, Lloyd Chalke and Jacob Morgan crossed for tries with Thompson adding three penalties and two conversions.