I have owned a 78 1300 Trillium and currently own a 1980 4500 Trillium with front bathroom, lavatory in the right front corner of factory molded in fiberglass and a toilet in the left front corner. The toilet is a like a portapotty but it is mounted to the floor and uses a standard rv black water dump valve under the left front corner. The toilet has about a 7 or 8 gallon black tank that is the base of the toilet.
The lavatory and kitchen sink connect below the sink and a drain is mounted on the left outside just behind the refrigerator
grill on the outside with a male hose end connector, you are to use short hose and a bucket to catch the grey waste water and dispose of it. There is no grey water tank in them. The 1300 has the same grey water drain on the outside and no grey water tank. I am the second owner of the 4500 and the first owner never made any modifications to the trailer at all. As a mater of fact, it looked like it had only been used a few times as there was no damage or scrapes on anything. Only a couple of the floor tiles were loose from being in the California desert and the adhesive let loose. The fresh water tank is wedge shaped and is mounted under a piece of 3/4 inch plywood under the dining table center section that also is the floor with a piano hinge and door on the front of it that lifts up to check the water level and to access the drain and fresh water pump.
Currently have a 2004 fiberglass class a motorhome that we travel in now. The 4500 has a high end 305 watt solar
system and is used for way outback boondocking
, 3500 lb torsion axle
and is raised 2 1/2 inches to help with ground clearance and is towed with a 2002 S-10 crew cab 4x4.