In short, Javelin is good but it is not a "magic bullet" by any means. If you control the rugged terrain beforehand (which Georgia did not), you can do a Hezbollah and gopher into the hillsides along the only usable routes for tanks, but Georgia did not have that option here. You may be able to get a few hunter-killer teams into place despite all of this via some serious mountaineering, but the size and bulk of the Javelin system means that they couldn't bring many in, they'd be able to take out a few tanks at best, and the Russians would just push the burning tanks off the road into the gorge and keep going.
I'm not sure I follow. What does the size and bulk of the Javelin have to do with anything, especially bringing in many systems? You can move them in the back of a pickup truck if you have to.