Record at 24 bits, set your levels conservatively, and don't worry about it. When you change your levels during a recording you alter the dynamic range of the performance. Much better to set them low beforehand, do not change them at all during the show, and then add gain to the show as a whole. This preserves the difference between the quietest and loudest parts and makes for a much better recording. With the low noise of todays digital decks and some experience with your rig, you should be able to get 16-bits+ of dynamic range with no clipping and no hassle during the performance this way.
It was really important during the analog days and to a much lesser extent with DAT but it really isn't necessary to ride your levels any more.