I agree with Blades here. It would make a difference if you never visited any preparedness related websites or even mentioned preparedness in emails. Keep in mind the government is filtering emails for suspicious words as well so the difference of posting public or sending an email does not really exist for them.
To hide your ip address you would also need a VPN or at least a proxy that the government has it a bit harder to see how often you access a certain website. You still have to trust the VPN provider of course that they do not keep logs or in case of using TOR you have to hope that you are not routed via bad nodes (some say that government agencies run some TOR nodes as well).
So you have basically two options. Completely stay offline and away from survival and preparedness related websites or gear up with VPN, proxies or use TOR and surf online like that.
If the government is after preppers they won’t look at vague profiles posted here, they will just get all records of your internet service provider and filter through what websites you have visited and how much time you spent there.
Given the NSA leaks, this process is most likely already automated and all major ISPs are part of this. I wrote a bit about this here: http://community.shtfschool.com/security/online-security-matters/
Alea iacta est ("The die has been cast")