The front feed on my 3880 doesn't require that the mat board and paper be attached. Assuming your 2880 works similarly, just lay your print upon the mat and make sure they both are aligned perfectly with other and that they register perfectly the right-hand edge and front-edge of the printer. (The only purpose of the mat board is to raise the paper a bit, for maximum fidelity).
Turning the paper size check option off is not necessary when making the print itself. It only became an issue on my 3880 when trying to run the second pass to lay down the GO... the printer sensor would detect that the paper already had ink on it and would refuse to lay down GO, even when presenting a 2" margin, per the workaround that Dana usually uses. I found that turning off the paper size check option allowed the GO to be deposited.
Your 2880 may not exhibit the same odd behavior as my 3880. I'd just print with the mat board using the manual front feed. And then try the GO pass. You might find the GO works no problem. If it doesn't, the first thing I'd try is Dana's standard workaround, described here, under the "Leading edge for glossy printing" ... http://www.inkjetmall.com/tech/content.php?147-Piezography-Gloss-Printing-Tips
As an aside, if Epson ever fixes the head-clogging problems in their larger printers I'll be buying one just to get the more sophisticated paper handling those models possess.