Many Thanks Neil.. the penny has finally dropped!
"The simplest way to set up an electrical system is to leave the stator grounded and have the rectifier output ungrounded. Take this ungrounded DC power to just the items that need it. It will be there for all your devices EXCEPTING a starter motor. This mixed system will work fine if you hook it up properly."
This is what I was getting at and, will do, if the guy at the testing station insists on the letter of the law.
From your description I think I will be OK to use a full wave rectifier attached to the white wire... Electricity is funny stuff....
Lets hope, for all our sakes, he just passes the bike!