1. l don't mind traveling all the way there even if it's only to see her once.
2. l don't mind traveling all the way there even if it ends up with me only seeing her once.
3. l don't mind traveling all the way there even if only to find that she has no interest in me at all.
Yes they are fine but a little long; some people would be that wordy other people will shorten the sentences.
1. Even if it's only to see her once l will travel all the way there.
2. l don't mind traveling even if it ends up with me only seeing her once.
3. l don't mind traveling there even if only to find that she has no interest in me at all.
2. l don't mind traveling even if I end up only seeing her once.
2. l don't mind traveling even if I end up seeing her only once.
It is possible to reverse the order of your sentences neither way is correct nor incorrect, also you will notice many English people either put the words also and only both at the front and sometimes at the end like in my two last examples. [only seeing her once. OR seeing her only once]
Whichever way you prefer is ok to use