The influence of ionized impurity scattering on the hole mobility in d-doped-channel AlGaAs-InGaAs quantum wells is investigated. Improvements by a factor of 2.5 were observed experimentally when moving a d-doped impurity plane across the quantum well towards an interface, highlighting the scope of selective doping and wave-function engineering techniques to enhance the transport mobility of such devices. Theoretical hole mobility calculations were performed and reveal an overestimation of the transport mobility, common to the random-phase approximation (RPA), that is much stronger for p-type structures than for n-type structures. This effect is partially attributed to an underestimation of the screening charge distribution width. Using a lower limit for this distribution of around 50 Å, it is shown that the RPA can provide accurate predictions between samples with different impurity distributions and densities.