Does he wear a belt too? Not sure I would trust it to hold the waist band. I have seen like a hook and eye closure but the "eye" has 3 different holes to adjust the waistband. I would try Velcro on 1 pair of pants before I did all of them. Velcro does wear out, has to be closed when washed and collects everything that comes even remotely close to it. I would not use the kind with the sticky back to sew on.