Wish I could say something useful about the Orbiter angle here, aside from observing that the water interface might be tricky to handle.
My dad is a docent at the Evergreen museum, where the Spruce Goose currently "lives." If you want detailed photos for the modeling, it should be no trouble to go up to the real SG and snap away.
I don't see any trouble with it opperating in Orbiter parameters. I would advise reducing the braking force on the gear/belly .ini section to more accurately simulate a water landing though. You might get some reasonable "bounce" that way.