Hi, Becky, and welcome to the forum. Thanks for posting.
There is no reason why you can't do a backpack trip while you're in W&W mode. And depending on the type of treatment you eventually choose (assuming it even becomes necessary; some tumors never grow), you should be able to go backpacking within several months following treatment. As a backpacker myself, I know this to be true.
I must say I admire your attitude. I was a complete train wreck for about two weeks after my diagnosis. With an attitude like yours, you're going to do great. And the fact that your tumor was discovered so early gives you a huge advantage on many levels (health maintenance, time to research your options, etc.).
With a tumor as small as yours, there is no need to rush into treatment. It makes sense for you to first have a followup MRI in six months to be able to tell if the darn thing is even growing; some ANs don't grow at all over the course of 20 years, although this is uncommon. Should your hearing, tinnitus and fullness symptoms worsen, however, I recommend you get two or three expert opinions on the wisdom of waiting before receiving treatment, tumor size notwithstanding. That's because you don't currently have any imbalance symptoms, and you want to keep it that way. The vestibulocochlear nerve (the branched nerve that comprises both the vestibular-- or balance -- nerve and the hearing nerve) is quite sensitive to irritation and pressure from a tumor, which is why your tiny little AN is already causing so much trouble for your hearing. The balance portion of the vestibulocochlear nerve is situated just above your hearing nerve. So what is now affecting your hearing nerve is likely at some point to affect your balance nerve, too. An increase in your hearing-related symptoms could possibly mean increased pressure on the vestibulocochlear nerve, which could at some point lead to balance issues. Treating the tumor could possibly prevent balance issues from ever developing. But it could also irritate the balance nerve and precipitate the very symptoms you're hoping to avoid. This Catch 22 is why, if your symptoms increase, you should get a few expert opinions on whether timely treatment is your best course of action or not.
In the case of surgery, the anatomical continuity of the balance nerve can be completely preserved and yet the function of the balance nerve can be compromised (by the stress on it caused by cutting away any portion of the tumor that is adhering to or wrapped around it). According to esteemed doctor Steven Chang (Stanford University Medical Center), however, CyberKnife radiation treatments (CK) are not likely to cause new symptoms you don't already have (e.g., imbalance problems) but may exacerbate those symptoms you currently have (fullness in the ear, tinnitus and hearing loss) if only usually on a temporary basis.
So you can see that you can never predict with certainty a win-win outcome with these risky treatments, although some outcomes -- mine included -- are phenomenally successful. You want to use the best judgments of the best doctors regarding if and when to treat. But do keep in mind that any increase in your symptoms should impel you to seek immediate advice vis-a-vis fully preserving your currently intact balance functions.
Again, you're way ahead of the curve, seeing as your tumor is so small and you have no balance problems currently. You are highly likely to have a terrific outcome to all this as long as you do your research and get at least 2 or 3 highly qualified opinions. Btw, Dr. Chang will review your MRIs for free and give you his free recommendation. He is both a CK practitioner (perhaps the most experienced CK practitioner in the U.S.) and a neurosurgeon. His email address is sdchang@stanford.edu.
Best wishes,
TW