That technique only worked for SH4. SH3 elements don't have a zone line. Try to move an interface object like the Notepad a few hundred pixels to the left (just increase the X offset of the main group). And see if it's cut off. I doubt it. I think it will show in full.
As for the image, just rescale one background in photoshop, for example the background image of the periscope. Make it as big as your screen can handle. I think that the game actually draws elements regardless of the viewport size.
Or just upload the dll file as it is. We'd work faster together
EDIT: Oh BTW, does the mouse work outside the 1024 box? We have to be able to click there.

)