The miniweasel only has a wingspan of 24 inches. You would probably have to get the weight down below 2 ounces to get flatland thermaling performance. Wingloading only determines how slow a glider will fly, but the span loading is a better indicator of the minimum sink of a glider. The higher the minimum sink the stronger the thermal you need to stay up  If the minimum sink of a glider is 100 feet/second then you need lift that is travelling 100 feet/sec up just to stay at the same altitude.
Span loading can be measured by taking the weight of the glider and dividing it by the span squared. The lower the result, the better the glider will thermal. You can see that the greater the span the easier it is to get the weight low enough for a good minimum sink. That's what greg was talking about when he said 'if the span gets any shorter than this (one meter) I notice a big fall off in performance'. As the span gets shorter, the weight must be disproportionatly lighter to get a decent minimum sink.
John
