TheBeerNerd had a good write up on this cooler, but it looks like the link to his site isn't working now. He used the existing port with an elbow to get the plumbing down to the bottom of the cooler and avoid the dead space at the bottom.
Blktre did a manifold on the 60qt version without the wheels. No odd-shaped lump from the wheels to worry about on the 60, but the idea would be the same.
I was planning on using the existing port with an elbow like TheBeerNerd, but after looking at the cooler I changed my mind. There's a pretty deep recess on the port exit and it comes out at an angle, so the placement seemed too awkward for me. Plus, the lid opens to the opposite side.
I'm just going to drill a new hole on the front of the cooler, right at the bottom, and use a braid instead of a manifold. Seems the simplest way to go and keeps the valve and lid opening on the same side.