Look, people are getting carried away with this. One does not need an ar'secrack for essential bodily functions.
Delicate stitching can seam everything up nicely. A talented surgeon can leave a nice little hole for venting purposes (in both directions if necessary).
Might have a little problem dancing like MC Hammer but Viking will be fine.
https://assets.vice.com/content-imag...butt-crack.jpg