If worst comes to worst, she could always go by Polly? Tripoli does sound like a kind of noodle, and the trip- part isn't very flattering. Everyone goes through some sort of clumsy stage in life, and it'd make it even worse if your name started off with "trip".
What about any of these:
http://www.behindthename.com/php/search.php?nmd=n&terms=tr* ?
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"The dog is a gentleman; I hope I go to his heaven, not man's."
- Mark Twain.