Neal, I have asked almost the same question some time back and I did not get any answers. Since then I have bought some stuff I have learnt few things about tethered shooting ..
As Neal (the other one ) mentioned Hal has posted some images of his tethered shooting rig. Joe Mcnally has done a nice blog post about his rig and you can find it here
As for me I have a Gitzo 1227 modified with a Markins TB20 and a Gitzo 3530LS.
After lots of research I decided to buy the Tether Tools Aero 15" because of its light weight and the rigidity of the platform. All the images I've seen of the Gitzo platform depicted it as a bit of a wonky piece of metal and that didn't infuse much confidence. I bought the manfrotto arm, various jerkstoppers from tether tools, a hard drive bay for tether table and a laptop securing strap along with the aero table and I'm mightily impressed with all the gear from Tether Tools.
After receiving the gear I mounted them onto my 3530LS and within seconds I realized that I did not have to buy another tripod. I basically unscrewed the arm and mounted it on the 1227 and has been shooting merrily on this rig since then.
In reality 1227 can hold way more than the recommender weight as long as you are NOT going to shoot from the tripod. If you load 20kg on this tripod and then mount a camera and do a long exposure the image might end up being blurry, but holding a laptop is something it can do a without breaking a sweat.
Whatever you choose please make sure that the distal most weight on the manfrotto arm is within the diameter of the BASE of the tripod, or else the whole thing will topple over. I achieve this by extending the second leg section of the 1227.
I mount the manfrotto 131DDB arm, Tether Tools Aero 15" with Aero XDC Duo HDD bay, MacBook Pro, 1-2 2.5" HDDs in enclosures, Markins M10 to "rest" the D800+Grip+24-70 or 70-200 on my 1227. Several times I have shot from tripod (with strobes though) without any issues.