A smaller excavator on rubber tracks would have the same benefits of a Jack-Pack unit as the excavator on wheels.
It even benefits more.
Since it fits inside of the container it could f.ex. be brought out to a construction site in the container and the truck driver will just drop of the whole set of container with the excavator inside it.
When the excavator operator comes to the work site he would simply fire up the excavator and drive it off from the container and position his machine in front of the container and hook it directly to a hook mounted on the blade and so the container will follow him around on site as he works. When it's filled up he calls for pick up and dumping.