those are fine but they don't have to be so long

Going on a biking tour and have been struggling with the same issue. Just bought some Pearl Izumi padded liners which look pretty nice and have a pair of Andiamo padded liners on the way, see which ones I like better. Might try the Ex Officio briefs linked above under them to avoid buying more pairs/having to wash the pads multiple times if they really work under padded shorts. Much easier to wash some quick dry briefs.