Doug,
Perhaps the photos on page 41 and 51 of the new Mega Thorn brochure will prove helpful:
http://www.sjscycles.com/thornpdf/THORN_MEGA_BROCHURE.pdfThese photos show a Tubus Airy rack...and mudguard stays mounted to it with P-clips.
Page 51 also features as options the Tubus Vega that "...includes adapters for use with BB7 disc on Club Tour or Mercury. We'll fit the M/G stays using 'P' clips as with the Airy. The Tortec Ultralight Rear Carrier is also shown, and "...works with BB7 Disc on Club Tour or Mercury".
Going forward, it appears a Tubus Airy rack might be a very wise purchase to consider *with* a new bike, as on page 51 Thorn also note...
The OEM carrier is supplied to us by Tubus, solely for fitting to brand new bikes. It comes with the Tubus bracket 22531 but without packaging. We can only sell this item to you when you purchase your bike. If you want one later the cost is: £153 for the carrier, + £3 for the bracket + £3 for the 'P' clips + £6 for the disc adaptor (sic) + £45 labour, that's £210.
It appears to cost "only" £100 if purchased with a new bike, all fitted and ready to go; a real bargain compared to buying later and attempting the parts sourcing, mods, and fitting oneself.
Best,
Dan.