I've never toprope soloed anything longer than a short pitch, but it seems like there should be a pretty decent solution to a number of issues, including overhangs, short traverses, and rope stretch at the bottom:

After setting the anchor, rap the route (wouldn't you need to do this anyway to get the rope running cleanly?) and as you do, set directionals on your way down. Then, periodically, leave the rope tied in direct to pieces (perhaps at stances).

Seems like this should take care of all of those issues, no?