It's easy, you simply use a weight retainer. The plastic ones will work, but steel ones are even tougher still.
You can literally add as many D-rings as you like, and put them anywhere you want.
Thread the webbing through the first slot on the retainer
then thread in the D-ring, and then thread the webbing through the second slot.
Weight belt retainers are designed to be put on 2-inch thick webbing, and to stay where they're put. This makes them ideal for holding D-rings in place, especially with the stiff webbing. They will not slide about.