*begin rant*
"Fair"? Uh, no. There is no "fair" that includes you doin' to someone what they don't want done. Goin' that path will get you single more oft than not, regardless of the gender you chose for a partner.
If a person tells you something is off limits, it's off limits. This is something I'm finding, more and more, that I appreciate about the BDSM subcultures. They DEFINE the do's and don'ts of their relationships up front. None of this "I getta, 'cause you getta". If she says no, no means no.
If you don't believe no means no, then you missed something somewhere in the last century, 'cause that line was drawn back then. This is a new century. "No" is a negation. "Don't tickle me" is a clear statement of negation. If you seek a reciprocating relationship, where you get to tickle and be tickled, you have to ASK for such, and get permission. No one's body is subject to the concept of "fair". We're all adults here, and should know this by now.
The legalities of such behavior also subject you to legal action. If a woman believes tickling to be sexual, and doesn't want herself tickled, you're not only assaulting her with your unwanted touch, you're risking rape charges. Special things await those folks, in prison. Some folks are into that sort of penetration. If she has a good enough lawyer, you face civil charges, too. You could be broke, in prison, for your belief in what's "fair".
"Fair" is a dangerous word in this culture.
*end rant*
'Ice, I do apologize for the vehemence of this invective, but that statement makes it okay to do what you feel, rather than what's morally, ethically and legally fair. Two of those are arguable. One ain't. Find out what she'll accept and allow, and more importantly, what's off limits. If a woman is bold enough to declare limits, respect 'em, please. It's a sad thing to picture one of us arrested, detained, and violated, for what stems from misinterpretation and misunderstanding.
What's bizarre about my stance on this is that I reciprocate for my wife. She tickles me too, and, to quote Boomtown, "I'm a tickler, dammit." While I walk your walk, 'Ice, I don't talk your talk. Even assumin' you're jokin', there's too much potential for people to mistake this for permission to mistreat a lover.
That would be bad.