The spring is what will effect the ride height. With more weight, you'd wan't stiffer springs to hold the load up. But you would lose some ride comfort. I do not know if they make stiffer springs for the Gen 3 Taurus, and if they do, I don't know how their availability is or what they cost.
I have a Gen3 and it sags really low in the rear. It turned out that my rear springs were both broken at the top. I don't know when this happened. There's so many big bumps and pot holes in Massachusetts it's rediculous. You can only weave around so many....
Currently driving a 2009 Focus SE Sedan w/5-Speed!
1997 Geo Prizm
1996 Ford Taurus G
Formerly "Mr. X"