The septic system was installed at the gray house. I had no idea how involved this would be. The tank was 1000 gallons, concrete, and took a large crane to install it. It has an input from the house of course but we also put one up by the RV parking so we could dump our future RVs and/or have a full hookup right there at the house.
The drain fields were much bigger than I expected. Instead of gravel they use what looks like ‘styrofoam’ peanuts surrounding the lines which I guess helps distribute the water around the fields. Pictures below show the various parts of the installation.