I would like to learn more about my 180D's flight characteristics at max. gross weight, particularly at summer's higher density altitides (I have a 7400' runway to work with), so I'm interested in knowing what you use for ballast? Sand bags are an obvious choice. (By the way, where do you buy those ubiquitous tubes you see in pick-up truck beds?) I was thinking boxes of my old law school books might work. It would be nice to finally put them to use. Smart-aleck responses invited and expected, but I'm hoping for some useful suggestions, too.