Correct if I'm wrong folks, but assuming C&G is within limits and assuming I can reasonably fit in the bird, soloing in a two seater shouldn't be an issue as they'd likely have a minimum useful load of at least 300lb.

You also have to get yourself into and (even harder) OUT of the glider. This can be a problem for people that are well under the placarded weight limit. Many pilots bring one knee up to their chests, then push up with one leg and two arms. If you're big and the console is fixed, then your knee will probably not clear the bottom edge of the console. Without the leg up, you'd have to use your arms. Might be possible if you're a body builder. How many 'dips' can you do?