Nice looking stock. If you think your husband will take more than a few hours which seems like a possibility, I honestly think the best option is just moving the tank you have somewhere else in the room. Even if you have to set it up on the floor. Yes you can keep the fish alive in buckets for quite some time but all the bacteria that encompasses your "cycle" is in the filter, at least the majority of it. You don't want to leave your filter sitting without food and more importantly without water. If it dries it dies.
It will be less stressful for your husband to build the new tank into the wall knowing the fish are all in their normal tank. Working under duress can lead to accidents or less than ideal out comes.