I just slap yellow on the whole bottom. If you are really concerned about the wax in the scales at the beginning of next season, just use wax remover. The yellow is soft enough that it will come off pretty quickly in cold snow, though.

FWIW, I wax the tip & tail of our "waxless" skis on a regular basis during the season. They seem to be happier for it. But if we go a few trips in between waxings...not a big deal.