I'm brand new to Esperanto (8 days as of this writing of this), and given that it is a constructed language, there is no region where one can go to for immersion. So my question is, are there any decent stand-ins online? Sort of an artificial region, if you will. It does not have to be purely EO speaking, I'm simply looking for a good EO community.
I will try to build a somewhat objective answer based on the information you gave us :
8 days as of this writing of this : since you are a beginner, it will probably be easier for you if you can ask questions in English. For this, you can use the Duolingo Esperanto Learners group in Facebook, Esperanto Stack Exchange, and the group Esperanto - English in Telegram.
a place where I can practice : If I understand correctly, you are looking for a place to use the language without having to find a language partner beforehand. Thankfully, such places exist. There is Twitter: Twitter is impersonal and short, so it is less scary for beginners. It is also a very good tool for immersion, since you can follow Esperanto speakers from everywhere in the world. There are also Telegram groups, which are chats (and cats) about specifics subjects. There is also the Esperanto subreddit: while the majority of users are from English speaking countries, it is a very good place to find resources to practice with.
make mistakes, be corrected : If you want to make as many mistakes as possible in order to improve quickly at writing, try Lang8 but since this website is not used a lot for Esperanto (you may wait a lot before a correction!), I will recommend you the Esperanto - English Telegram group. Because if you want to be corrected, it is much better to have direct feedback from several people, so this kind of chat is ideal.
There are many more Esperanto communities, but as much as I am trying to be objective, I think Telegram groups are the best for beginners who are willing to practice and to be corrected.
There is this site called Esperanto Language Stack Exchange that I heard is pretty good.
Just to talk a bit about my experience as a beginner: I encountered Esperanto at the Polyglot Gathering in Berlin.
Afterwards, I kept in contact with these people.
And right before the IJK (a congress that took place in Poland this year) I discovered Telegram!
Check mondmapo and ask in the Esperanto groups if there is anyone near you! I went to the local club, but I mostly meet friends informally instead of going to club meetings anyway... and I use Telegram every day. Now I'm pretty much fluent and I really enjoy my language journey. Welcome to Stack Exchange and welcome to Esperantujo!
One site that I've used in the past, and has been around for a long time, is http://lernu.net. It looks like the site has had a complete redesign since the last time I used it, but I think all the same content is available.
http://www.reddit.com/r/Esperanto is very welcoming to beginners, I know because I'm a mod there!
I rather like the ##esperanto IRC channel on Freenode. (try the web chat https://webchat.freenode.net/, entering ‘##esperanto’ as the channel name)