I hunt while carrying a Glock 20 and use exactly this holster, only with belt loops instead of the paddle. The holster comes with both, and it is easy to switch back and forth using the supplied allen wrench. It is not an attractive holster but it is quite utilitarian and I don't mind getting it wet and if it gets dirty I just wash it out in the sink and let it dry.
I also use a Hill People Gear kit bag when wearing a backpack with a belt. I tend to hunt pretty lightweight, wearing a HPG Tarahumara pack and wear the G20 in the belt holster. If I switch to a pack with a belt to haul out meat, I put the G20 in the Kit Bag .
I was into 10mm Auto before it sold out and went mainstream, but these days I'm here for the revolver and epidemiology information.
Thanks for all the feedback and advice on this folks. Plenty to think about. I think you're right in suggesting that, in this case at least, it would be better to ask him exactly what he wants rather than trying to guess. He's a bit old for surprises anyways. Thanks again to everybody.