I've used one UTH for two tubs before. Unless you can get a pretty solid material to split the 20 long in two that covers it completely and doesn't budge, probably just put two totes back to back with the uth on the side, or, if not that, under both of them. I'd only consider this if it was a sealed plexiglass divider and you were able to meet the right heat for each species on both sides.

If it's super temporary, say a few days to a week max, you could go without heat if you don't feed them. As long as they're kept warm enough, they should be fine. I've had to move so many times and I've had animals off heat between 4-7 days while setting everything up. Just don't feed them and you won't absolutely need the heat spot until you can get it.

Otherwise, just use two totes for now and split the uth between them or use handwarmers under the totes for a few days if you have them.

You could also consider using a dark tote and putting a light spotlighted at the side to warm it, or borrow a heated blanket/pad from any woman you know. Most women would have heating pads for that time of the month

I always try to keep extra heating pads on hand even with a rack system just in case. Things happen. I wouldn't worry too much, the important thing is making sure they have a tank in the first place! Sounds like he doesn't have enough tanks, so even in just a warm room they'd be better off.

A huge bag of hothands from costco is usually like 10 bucks. That should cover switching them out consistently for a week or so. Heat cable is cheap too.