Panasonic GX1 and the Panasonic 100-300mm lens?

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As you can tell from the pictures, the 100-300mm lens isn't a small lens. I really did wished that Panasonic made a collar for this lens. In situations where I have to use this lens with a tripod (Gitzo GT1542T and the RRS BH-40 ballhead), how will this fare in moderate to windy situation? Initiailly I thought by going with either the Panasonic GH2 or GH3 may help alleviate some of my concerns because they're bigger and heavier cameras, but the weight distribution still doesn't look right. Part of me thinks that performance with the GX1 will be the same as that with a heavier camera as long as it's held on tightly to the ballhead. Nonetheless, I am concerned that my setup may be useless and that I'll get soft pictures when the shutter speed is low. Is my concern warranted or that the GX1 will perform fine even in the 1/4s situation as a GH2/GH3 would?