Eventually, you're going to need a rivet buddy. Surely there's someone who might actually enjoy helping you do this, and the top wing skins are a good place to start out. Good access, good visibility, no awkward positions...at least until you get to the bottom skins. If you ask around, there may be someone at the airport that would enjoy having a part in building a plane.
Even though my wife had absolutely no interest in building a plane, she shot all the top skins on the wings while I bucked. She did a very good job--and we're still married.
Is it possible to put the leading edge on after the top skins? I'm trying to visualize that and I can't see why not. But eventually, you're going to need some assistance or some very long arms. I've heard tales of people back riveting all those rivets on the top wing skins, but it seems like an awful lot of trouble to go to.