Cheers Chris,
that info has thrown a different light on what I can or not do,will have to do a bit of research into what's available/suitable based on what you have outlined here. 
My rears are 265 so the bias towards inner edge wear on mine is slightly exaggerated. But, given the rear tyres are within 1mm(inner) to 2.5mm (outer)of replacement I certainly wouldn't go any lower than the 20mm lower than standard it's set to.
I'd expect to see that inner remaining 1mm disappeared by now, and both rears neeed replacing yesterday if it was at 30mm lowered.
Don't get me wrong that's ok of your aware and make a decision to accept that level of wear knowing the consequences, but most people aren't, and recommend to others. The other aspect of excess camber and associated tyre wear is straighline stbility stuffers, and tram lining comes in to pester the driver much earlier. Which mine has been for the last few months.
Vx may have been lax with their front camber setting tolerances, but as said, there's a very good reason why they only lowered the mv6 by 15mm from stock.