Another alternative to lying is playing the stock comp games companies play. "My comp has a large stock component, and as you know, it's tough to put a dollar number on it. Given current valuation estimates/growth trend/TAM/exit hopes/whatever, I'd estimate my total comp around [the high end of what I think you would consider reasonable]."

If they say it's too high, then you can say you might be willing to take a little less, potentially, for more of that to be cash/public liquid options/predictable/stable/whatever.