In the past, I've added up the value of my base salary, any bonuses, OT, plus any fringe benefits and presented the total as if that's my going in salary base requirement. Yup, fully aware that it's kind of sketchy, but screw those people who insisted on knowing a current or past salary. If they really persisted, I would say "oh, yeah, that's total compensation", but that never happened and I always got pretty close to what I asked.
Also, there are a TON of people who are vastly overcompensated at the expense of others who are undercompensated. Which one do you want to be?