If he removes his shorts alltogether he probably won't even notice the hotspots.
No really. Thinner socks, no black socks (Black absorbs heat), loosen your shoes, try some different insoles, then try cutting out the area of that insole directly below the area that burns. Go to a Podiatrist and get an Orthotic made for you. The Orthotic should do it if nothing else does. I may go that route myself.
Really Blazingpedals, telling the poor guy to loosen his shorts.