I would go for bibs instead of shorts. IMHO, they are far more comfortable due to the lack of waistband. I've got a couple of pair of the Falconis from Love2Pedal and they are awesome. And only $36 w/ shipping (and I think there is still a discount if you type "CLYD" in the coupon spot) and, though I haven't needed it, they have a great return policy. I wear a 38 waist in pants and the XL fits me perfectly so would think the XXXL would fit as he wears 44 wast pants. And I wear gym shorts over them on occasion as I am a youth leader and take teenagers on rides occasionally. Figure they have enough trauma in the world without seeing me in spandex.