[Bicycle Bob]

In a steady cruise down the highway, stability is pretty easy. The first tricky condition is the crosswind, often a gusty one around big trucks. A light, streamlined vehicle will generate a lot more side force relative to the traction available, and, unfortunately, that is always concentrated near the front. So, it is better to have more weight and traction at that end. Ideally, you would have positive stability with no traction at all, like an aircraft.
The other tricky condition is the emergency maneuver. Just weakening the front brake will add some directional stability, but it looses stopping power. That reduction only helps in proportion to reduce the danger of tipping if you steer while braking. Some days, it might be better to lock up the front, so you can't steer, instead of getting skid-induced oversteer.
There are delta trikes on the roads, but their insurance rates reflect the amount of extra room they need for safety.