You don't need to dig down to install a predator apron. You simply very securely attach a 2' wide strip of 1/2" hardware cloth to the base framing of the floor all around the coop, secure the opposite side with landscape pins then cover the HC with about 1" of soil. You can plant grass over it or whatever.My biggest concern is figuring a way to dig around the base to add hardwire to make sure nothing digs in.
I would think that trying to use anything other than DLM with a dirt floor would be labor intensive. The beauty behind DLM is that the microbes in the soil break down the waste via decomposition right there in the coop. You either rake the litter daily or toss and handful of scratch over the litter and let the chickens do it for you. Add more litter as everything breaks down. It's simple, healthful and greatly reduces chicken keeping chores.