Doing business - Is this enough overlay?

[phydaux]

I play NL cash games, mostly on the internet now but I'm looking to playing live regularly. And I'm thinking about regularly offering to "do business." The two things I'm thinking of doing are offering insurance and "buying the dog."

What I'm wondering is is 10% overlay enough, or should I ask for more?

For example, if someone is all in, they turn their hands over and the favorite is 80% to win. I would offer insurance at 22% of the asked amount. If they were 90% to win I would offer insurance at 11% of the asked amount. So I would be getting 10% more than the correct odds.

I'm also thinking of offering to buy the dog hand. If the had is a 20% dog, then I would offer the player 18% of the pot to buy their hand. If they were a 90% dog, I would offer 9% of the pot. Again, a 10% overlay for me.

I'm thinking with "just" a 10% overlay there would be massive swings and I would need a huge BR in addition to my regular poker BR. But if I try to squeeze out a 15% or 20% overlay then I'll never get any action.

Thoughts?