Dudley your experience on the Watsons Bay line I think verifies why Maddocks saw the R/R1 as a tier 2 tram in terms of capacity. Nominally, it could carry as many as an O or P, but the fewer doors (still more generous and better distributed than an SW6 would have offered though) meant that the practical prospects of loading to that capacity in a short dwell were slightly poorer.
As for trying to run loading experiments on the various classes at Loftus, I fear that too much human "evolution" has occurred (thanks to fast junk food) to replicate conditions of the 1930s. I look at the photos taken inside R/R1s in the 1930s with everybody tucked neatly into their seats and then I look at my photos inside similarly crowded trams at Loftus and the aisle is narrowed to a slit by hips, thighs and robust legs bulging sideways from the seats!
Perhaps the crowd will have to be recruited from Jenny Craig.