The best way to control your extension pole is to reduce the pressure at the tip by using a larger tip. I've never used the belt I have now, though I'm sure it wouldn't be a bad idea. If Mark doesn't sell them, I'd be happy to direct you to a source. (No, I don't sell them! lol)
(Just in case you don't know...On each tip, there is a number, say 40040, which is 40 degrees [white tip] and a orifice size of 4.0. By using a larger diameter orifice, you will lower the pressure - but not the volume - at the tip. This will make the extension much easier to control.)