6 hours isn't long for a older pup or adult, so it would only need to be for 2-3 months that you would need to worry about giving them a break midway or two if possible.
IMO The best case scenario would be involving a neighbor, family member, or bonded pet sitter to come let the dog out once a day if possible. I personally don't like giving a pup a chance to potty inside unless it's the only option.
Otherwise I would go with the enclosure in the basement
Jasmine - Female Miniature Poodle - born Aug 15, 2010
Loker Delgado Von Stalworth - Male GSD - born Jan 26, 2012
Koda & Zazu - 5 year old male cats
Alex - Male Cocker Spaniel (rescue) - RIP Cuddlebug 2007-2010