I'm no at home to access pictures at this time
The process of lowering the tanks wasn't that difficult
I used steel "studs" from a supply house. Actually they are the bottom chord for attaching studs to the floor.
Heavy gauge and approximatly 8 inches wide.
After removing the gray water tank I cut the metal stud to length then bolted to where the bottom of the tank used to sit
I used epoxy covered plywood beneath the tank and the bottom flange of the steel stud
I insulated the area where the tank used to sit.
The grey water tank then just slides in
Of course the original sheet aluminum covering the bottom or the tanks won't be able to re use.
The inlet elevation should end up so your new inlet pipe will be going thru a factory hole in the crossmember
You will have to replumb the grey and black water dump valves to exit below the frame instead of thru it
I was able to keep the valve levers in the original locations
On my airstream the drain pipe for the kitchen and bathroom sinks, along with the shower were above the floor
I had the reroute this drain below the floor as well to lower the shower
I'll try to find pictures