I don't see any need for boots for hiking/packing in the Southeast, any time of the year, unless you're tromping through mud, and then I'd recommend a different kind of boot. Good non-Gore-Tex hiking shoes will be fine, and his feet will stay much cooler, and socks will last longer before becoming saturated with sweat. No cotton socks. Either synthetic or wool of appropriate weight. Someone said 2-3 changes, I think that's fair. I'd bring more because I have sweaty feet. I've hiked portions of the AT in Georgia, N. Carolina/Tennessee, and Maine. My shoe of choice for longer trips (heavier pack) is the Sportiva Boulder X with Superfeet. They're stiff, supportive, and comfortable. I'm biased, though, and wear them pretty much everywhere - I'm on my second pair in four years.