Go to the Thetford website and look at the instruction manual for the 700. They require installation of a mixing tank into which both black and grey water flow. The macerator is in the mixing tank, and that tank requires access to the bottom to perform service and repairs of the grinder/pump system. This generally requires a service panel in the subfloor of the RV.
This unit is an OEM installation item due to the amount of room required and the plumbing needed. I have had a few inquiries about such an installation to replace the in-line macerators, but the labor cost has been exorbitant due to room required, floor removal, tank removal, plumbing, and new installation.