We investigate ramifications of the persistent spin helix symmetry in two-dimensional hole gases in the conductance of disordered mesoscopic systems. To this end we extend previous models by going beyond the axial approximation for III-V semiconductors. We identify for heavy-hole subbands an exact spin-preserving symmetry analogous to the electronic case by analyzing the crossover from weak anti-localization to weak localization and spin transmission as a function of extrinsic spin-orbit interaction strength.