Don't worry about finding an area that this tattoo is going to hurt More or Less. It's a Tattoo, it's not going to be pleasant. But, You will make it through it just fine. Instead, worry about where you want this particular tattoo; Get it there regardless of the perception of pain associated with that particular area. The pain is temporary. It hurts while I am physically tattooing you. After it feels akin to a sun-burn. When it's healed, you won't remember the pain. You will however, have a tattoo where you wanted it. In an place on your body that you will fondly look back upon in years to come and know that you made the right choice.
Basically, there is nothing wrong with a white tattoo. I get it; you can easy conceal it; it doesn't attract attention the way a solid black tattoo does; The fact is, you can barely see it. So it's easy to hide from parents, from judge-mental friends, and current and future employers. And you can even look cool to your friends, sexy to the opposite-sex, and seem like a bad-ass that's breaking the rules, without having to really commit. But have you considered EVERYTHING about getting a White Tattoo?