Some of my 1000+ gram snakes only poop on average once a month or longer in some cases. I wouldn't worry about it especially if gone for only 2 days. I've got an 8 day trip and I'm not worried about it.
As for the towel thing, I'm not sure what you're talking about? Do you mean you cover their whole tub every night with a towel?
Lol I cover the front of their rack to hold heat at night although now that it's summer it's probably unnecessary.