1) Is he limiting his fluid intake in the evenings?
2) Which inserts were you using?
3) Is sewing up your own overnight trainers an option? You’d be able to make them as absorbent as needed.
4) Can he set himself a vibrating alarm clock to wake him up twice a night?
Of course you’ll need to do test runs of whatever it is you’re doing at home first but you may just find a good solution.