This is an interesting problem.

I worked professionally in vehicle dynamics and suspension design.

There was a very good university study about 15 years ago, proving that gyroscopic stability from the wheels, and castering/trail, were not necessary for bike stability, IF the center of gravity was forward of the steering axis and high like you have, this caused their vehicle, when rolled with no rider, as it leaned ( began to "fall"), the bike would steer in that direction to self-correct. So usually, the weight distribution that you have would be good.

That is not the case with your bike, which has a much more complex front suspension linkage. I would suggest lowering the front cargo height, but that is impossible, due to the wheels leaning in camber in turns; Picture #4 is the most important one.

First, with a front and rear cargo load that seems unstable, remove the rear load, to see if the rear cargo height is contributing to the instability. Because if it is, you can lower the rear cargo height using panniers, with heavy things in the low panniers.

If rear cargo height is not a factor.... well, you cannot lower the front cargo height between the wheels, as the tires will hit the cargo basket.

You are proposing greatly changing the steering geometry, to move the front cargo load back, however the steering change could have a detrimental effect. I wish I could see more details on the current steering and revised steering. Increased moving mass on the steering can be bad; General Motors discovered this in the early 1970s when they tried to apply the steering geometry of a Mercedes-Benz to a car with much heavier steered mass, and it became unstable, they needed to add a steering damper.

My suggestion would be to invest in one of the cargo bikes with a very large, low cargo area between the handlebars and the front wheel, with pushrod or cable steering to the front wheel. I cannot think of the generic name, but Bullitt is one brand. Due to the wide use, I expect they are quite stable, even when stopped, as the load is low enough to have much less moment arm to tip you over. A dual kickstand (center stand) would be good for parking.