By organizing in more voluntary ways. You do know that there was a highway system before the interstate was built, right? We had roads before governments started builing them. We don’t have many private roads anymore, but then a large competitor with the power to tax and no responsibility to return a profit will do that to a marketplace.
Some of the best wildlife refuge areas are privately owned. Simply put, if enought people decide that it is important enough, any of the things we do now (along these lines) can be accomplished without the government.
I’m not so sure. Any such society (from scratch) would have to be pretty small. It seems far more likely that a small group would be able to declare themselves libertarian. While a larger society would seem to me to have much more political baggage to undo. It has been my experience that undoing political structures is much harder than creating them from scratch. I’m not sure that this is a general rule, though.