I would like a decent holster for on the waistband carry while I'm out hiking or in the field for a HK USP 45? I'm not opposed to other methods but this seems to be the best considering the size of the weapon. Thanks.
Assuming open carry is OK in your area, an OWB holster isn't a bad idea for hiking. I'd suggest a little more than just tension retention, though, just in case you take a spill.
I haven't used it personally, but you might want to check out
this holster from Bladetech. Thumb break retention, and it's a paddle so it'll be a little easier on and off when you stop to make camp. I have an IWB bladetech that's been pretty good to me, just needs a little adjustment every now and then.