nanna-up-north

Hi. I'm making a quilt for my son and he wants minkie on the back. I've been told to put the stretchy minkie going across the long arm but it's not wide enough for this quilt. The flimsy is 65" and the minkie is 59". So, should I make a seam going up and down the quilt? (I've been told that's a no-no) Or should I turn the minkie with the stretchy going up and down and then the seam would be going across rather than up and down. Help. I'm pretty new to LA work and this is my first quilt with minkie and this problem.