In these last photos I show how I have connected the camera to the tripod collar of the lens. This has the effect of making the whole combination more sturdy and inflexible and providing a means of adjusting for the center of gravity on whatever support you are using. It also makes a for good carrying handle ! A commercial version of this can be found here - http://www.ebay.com/itm/140971397996?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT#ht_2636wt_1325 - called a "splint".

Since none of my longer lenses have IS/OS/VC, and since I regularly shoot at 600mm, I have been on a quest for maximum stabilisation techniques for some time now. Having adequate support for the lens/camera is a big part of the equation. But beyond that, there are still other things you could/should do. On longer lenses, having a firm grip towards the front of the lens works well for me. Pushing the camera against your face at the moment of exposure is another sharpness technique with high merits from my experience.
So, my first thought was to install an extended eyepice on my Canon's - and that was better. Then I thought, I really need broader contact areas for even better stabilisation properties and comfort. I searched the net and found nothing of what I was looking for. So, I decided to make it. I went to Ace and got a "T brace" that had some holes already drilled in it and bent the "T" part at 90 degree angle in a vice and installed a piece of self stick insulating foam to the "T" part. I then ordered off ebay some metal feet that fit in the accessory shoe on the top of the camera with a 1/4-20 stud - for the forehead brace. the bottom chin brace is held by a screw in the tripod socket. This results in exceptional stability and comfort ! - and makes me wonder why I have never seen this or thought of it before in my 40 + years in photography ! See below........
I now consider this hardware/technique to be indispensable in obtaining maximum sharpness at 300-600mm focal lengths. You will also find this keeps sweat from getting into your navigation wheels and other switches on the back of your camera. It also affords you a little more room to use BBF if you are left eyed like me.
If anyone knows of the commercial availability of similar hardware, please let us know !