I've reconsidered my rather flip answer earlier after doing a rehearsal of all the poses I could think of and actually most of them are restricted by clothing. The balance poses particularly are hindered by clothes, e.g. the tree pose, a favorite of mine with heel of one foot planted next to balls on inner thigh and hands raised straight up -- a beautiful pose but my foot always begins to slip and then I become tree with broken branch. The rapid transition poses also are hindered with clothes, e.g. sun salutes transitioning through hop to flank and downward facing dog hopped to upright poses, standing to lunges and most of the warrior poses, which I think are some of the most magnificent postures that either the male or female body can be displayed in (I always have to adjust pants to get my legs just right). Only ones I would prefer not to be naked in would be the backbend poses. I would think that a thong such as you are wearing would be helpful in keeping the package secured for some of the squats-standing transitions or others where a lot of chaffing I think would result with all that meat in the way.
Since I have been ridiculed since first grade for having perfect posture, this is a perfect outlet for me to enjoy and firm up that posture, which others I suppose are envious of, and is a primary objective of yoga. A down side for me though would be my lousy physique that I always keep hidden in loose fitting garments. However in some of the power poses I think my stringy muscles wouldn't be noticed as much because of the majesty of the poses. Go for it, if you have indulged in pilates (that is very hard for me) and have the body displayed with your name, I would be suprised if a camera crew did not show up when you positioned yourself in warrior I pose (my very favorite for its look and very, very difficult pose to do perfectly with warrior II being a good one too).
