The changing temperature also wreaks havoc on the inner thighs. Going from sweaty-hot to cool always makes it worse.
Boxer briefs plus vaseline works great. Make sure to shower after each day's show, put on clean skivvies with soothing lube at night. You should be ready to tackle the next day in well-oiled fashion. The boxer briefs will also protect your outer layer from getting greasy.
The worst down-stairs heat related problem is "golfer's arse".
A horrible sweating, chaffing, itching, tickly condition caused by walking miles in the middle of a really hot day wearing a pair of trousers and not shorts.
The best knwon cure is getting naked but most golf clubs have a policy against such nonsense, Im guessing coachella will too.
Wear compression shorts under your baggy shorts, like the kind football players wear, you can get them at Wal-Mart. Also powder stick deodorant is the cheapest way to go for a topical treatment, plus you can buy travel size all over the place, don't know if they make it in men's but at least if you buy Dove your thighs will smell powder fresh!