Rating Plate Upgrade for MTPLM

hitchglitch

I have a Bailey Unicorn Valencia and remember that when I purchased it last year there was mention of being able to get the maximum allowable weight (MTPLM) upgraded and rating plate changed (for a fee of course!).  We have a mover and fixed canopy and I
am concerned about the allowable payload. Does anybody know how this works and whether it is possible to get this done on a used van or is it just an ex-works option?