Steering Stabilizer v2.0
This version has a much longer crown-mounted lever arm (I used an old rack strut), and still uses the dual springs. Now we're getting somewhere! I lengthened the lever arm even further than shown here (by moving that bolt) and noticed some improvement. The bike still feels pretty floppy, but it's improved over no spring at all. Still doesn't feel as neutral as a low-trail bike, though.
Riding the bike w/o any front load, it feels very much like riding a low-trail bike w/o a front load, too. Hmm...interesting!
I was surprised by how much spring tension is required to have any sort of impact on the steering. I actually bought other, lighter springs than these, but ended up not using them. Making the lever arm longer is one way to compensate for a weaker spring, since torque = force x length.
I'm going to have my wife ride it, and get her feedback.