No problem!
Also sorry it took awhile for someone to get back to you. I did see your post yesterday but thought I'd leave it for someone that uses tubs to answer. The rule about enclosure size is just what I've always been told about any other type of enclosure so I assume it would work with tubs as well.
Full disclosure, I have no experience with racks/tubs, so if someone who does gives you different advice I would defer to them.