Thanks for all the great comments

Ashtray seemed to be the tidiest solution to me, but there are plenty of options - I considered removing the R/H centre air vent at one point but as my phone is in a holder up there on a dashmount bracket it's a little awkward to access. Limiting factor of the ashtray is the depth / size but this module fits just fine.
As far as the modifications to the head unit, it is well documented on the Internet, Hardwarekiller's site amongst many others have the instructions, all very simple stuff, but the more difficult side to it is routing the cable sensibly and using a plug and socket arrangement (If you've got an NCDC/R you will need to take the unit out for a Nav Laser at some point!) to enable the head unit to be removed.
NCDC 2013 / 2015 are physically identical, it's only the presence of a Telematics on the CAN bus that makes a 2013 a 2015 (except a few legends on the Bezel). NCDR 1100 / 1500 are identical to each other in the same way but there's a slightly different method of interfacing as the CDC3 unit is a physically separate unit.
By the way, I take no responsibility for anyone who damages their unit trying to get it out of the car!