Tips to use Glidecam 2000 in Wind?
 

Seems to shift it quite a bit (using Canon Optura 20), no weights on the bottom since the thing is so light.

Therein lies one of the weaknesses of a passive stabilizer (meaning any Steadicam-type device as opposed to an active stabilizer which requires devices such as gyros): window is a problem. Your best bet is to shield yourself from the wind as much as possible, which requires the help of at least one other person carrying a windblock. There are various schools of thought on this. Generally it is agreed that a block that allows a small amount of air passage will be better than a solid object, as the wind can swirl unpredictably around the solid object; hence, a 4x4 double net makes a better windblock than a 4x4 solid. Have the blocker hold it vertically between you and the wind, and as close as possible. With a small device such as a G'cam 2000, you can probably get away with a 2x3 net, but the larger the block the more effective it is.

Other solutions are much more involved--adding gyros is an expensive and power-hungry way to go but will resist the wind nicely. Glidecam has demoed a system with gyros but I find it hard to believe that anyone would pony up that kind of money (the gyro system would probably cost about 10x that of the rest of the rig!)

Sadly, there is no quick and foolproof solution. And the lighter the rig, the more prone it is to wind interference. You can use a somewhat stronger grip with your guide hand, but of course that will compromise a bit of the smoothness of the operating.