The guys at Option 1 Nissan say those C collar kits really do the job and fit in under 30 mins, without removing the subframe.
Not exactly sure which camber bolt you mean Leigh, but the WhiteLine upper arms have their own adjustment and you can get the required settings (usually about -1 deg for street use). With the standard arms and the factory setup for the coilovers, the best you can usually get is -3 deg. Way too much.
:: Japanese Motor Sport Online Store :: - R32 Whiteline Adjustable rear upper camber arms