Thanks for your help, much appreciated.
Who would have thought you needed to be an engineer to attach a camera to a tripod !
You don't have to be - just pay. But if you're handy with a few basic tools, it helps!
This is what I'd do in your position. Buy a cheap universal L-bracket - I bought this one for £8
http://www.amazon.co.uk/XCSOURCE®-U...28332801&sr=1-1&keywords=arca+swiss+l+bracket just to see if it was any good really. It was, but could be greatly improved, so I set about it with a hack-saw and file. It now fits my 7D like a glove, snug to the left-hand end, with a cut-out for cable access and a nicely rounded corner that doesn't dig into your hand. Could do with some touch-up paint, quite a lot actually, and I'd still have your problem with cable access for vertical framing if I didn't use the IR remote.
I'd solve that with a spacer, made from these two small clamps for £17
http://www.amazon.co.uk/Neewer-Alum...=1428332922&sr=1-48&keywords=arca+swiss+clamp attached either side of the cut-out and joined by a £5 60mm A-S plate
http://www.amazon.co.uk/PU-60-Quick...8333211&sr=1-3&keywords=arca+swiss+60mm+plate Both the clamps and plate would need a bit of filing and drilling. You'd then have an L-bracket that could be left permanently on the camera, with the spacer attached for verticals

It would work pretty much like this Kirk spacer
http://www.kirkphoto.com/LBA-1_USB-AC_Spacer_Block.html# though that also requires some work for Canon and it needs an Allen key to fit and remove.
Here's another idea which, thinking about it, might be the best option. Get that universal L-bracket, and any A-S clamp that takes your fancy. Bolt the clamp to the top side of the bracket - job done, no cutting or drilling. You'd end up with something that looks like this
http://www.ebay.com/itm/Universal-L...mberley-acratech-wimberley-foba-/330893511815 Acratech also do something similar, and probably others too, but only at a price. The above solution would cost les than £15
