No I don't think it would be a good way to judge interest in the site. I was using the site before I made an account to look for the obvious; info on the Peace Corps...I found the site helpful. However most people won't/don't pay for use of websites. I know this because a friend runs a political based site/forum that has a decent Alexa rating, gets an impressive amount of views each day, and has been successful for 8 years now with 60,000+ members with accounts and a great amount of regular guest views each day. However when he tries to fund-raise it is like pulling teeth. No one (I take that back, some ppl do, most do not) gives money to websites.
That being said the few times he has mentioned closing the site; you'd think it was the end of the world with his members, they love the place, they cry, they write lengthy posts about why he shouldn't close it. People love it, they use it, they just simply won't pay for it.
I will donate some money to the kickstarter, and I hope you are able to raise enough to keep it open. It is better than reddit in my mind.
However if you do not raise much, don't take it as a sign that people don't like the site/are not interested in keeping it around/have not found it helpful, it simply means what almost any other forum admin/websmater will tell you; people don't/won't pay for websites with a few exceptions.
You should not be solely responsible for the financial aspect of keeping it open, so I understand the desire to fund raise and I think it is a nice idea an you should give it a try (although keep in mind your audience also...PCV's who don't make much $ and invitees who are going through medical clearance expenses....), but like it was said above don't be too surprised if you come up a bit short.
I'll keep my eye open for the fundraiser/kickstarter