I am thinking again about your Dehon. The brace on the mast gives it a very straight head angle. It almost looks like the contact patch is ahead of the steering axis. That is, negative trail. Or at least very little. Looking at other 16ers they have a normal head tube angle and the handlebar mast is angled above it. Have you ever considered turning the fork around? It's a common joke about Walmart bikes but it works ok because it increases trail. Then it would kind of resemble scooter steering. It might give you too much trail, but it may be better than negative.

Obviously this is crude but you can see what I mean