The race ware adapter looks interesting, but I note it is sold out. I got one of the k-edge mounts but I couldn't find in the the uk, I'm having to get it sent from the us.
In the meantime my old joule head unit has died and as the 500 was going for £129.99 on amazon a few weeks back I got one of those, I like a map and other info when I ride
Guess I'll put the 500 out front and move the 705 to the bar. Not ideal, but it will work and let me get at the route sheet easier.
Now all I have to do is figure out a way to power two Garmins on rides over 150k