One thing to always use when you are not sure your settings are correct or you are trying something for the first time is to activate the print preview in the Epson printer driver. While the view in this preview is not color managed (making most people question its value and existence) it is really intended to give the user and accurate of image placement on the page. So, if you activate the print preview you should have seen a preview that would have shown the small image in the middle of a long sheet.
The only thing I can think of is that maybe you didn't save your custom paper size? I have heard of a lot of instances where users skip this step inadvertently. You must save your custom paper size before you exit the dialog box. Once saved you can select it from the drop down in the User Defined section of the paper sizes.
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