It's not just a hole, look at the other pics.. It shows a molded square port going above the terminal connector on the back and behind the sub opening... I thought the same thing at first glance
I have to agree that you want to go with the recommended sub or a comparable sub... Will it work? Yes... Will you get it perfect with that enclosure? No... But most don't notice and just want some type of bass... Do what ya want bro and let us know what you think...