The best thing I have found are some Duofold Coolmax stretch shorts from sierratradingpost.com. They kind of look like bike shorts but no padd and the fabric is lightweight and very silky. The seems are nice and flat. Unfortunately, they no longer have any of the men's. In desperation I ordered a pair of women's as a trial. They seem exactly like the men's; even the sizes seem to run the same. So, yes, Rainman is wearing women's underwear. They only seem to have size small left, but they are a good price if you can use them. There are two models. I have tried both. The black ones seem to be slightly heavier fabric but you can hardly tell.

While you are there, Joe, check out the Deuter cycling backpacks Fubar mentioned. Do a brand name search on Duofold and Deuter.