It is difficult. To be honest, if it’s dry I’d leave them. And wait till it’s time to do a substrate change and prune the hoard then (ie replace about half the substrate then). Am assuming that he has pee’d down there in which case it’s necessary. Could you give him 2 houses? Our Robo has a great system of moving between two burrows. So I could spot clean one (he’d then move tomorrow the other one. Another time I’d spot clean the other one and he’d move back to the first one