So reading the documentation is a good thing... who knew?
I went back and worked on the custom MailChimp template and tried to figure out why I couldn't add text to the main body of the email. Turns out you need to add some custom attributes to the element. From what I understand you can use div elments as well as table cell td elements. So adding:
To a td element allows you to edit the "field" when creating your campaign. The MailChimp Template Language documentation was very helpful in figuring out why MailChimp kept wanting to attach their own footer to my template. Turns out I didn't implement all the required Merge Tags needed for the free version. I initially grabbed the fields from the example template, but for whatever reason didn't keep all the ones I needed. Probably because I thought they weren't needed.
Another problem I blasted into with the footer was when I included the |HTML:LIST_ADDRESS_HTML| tag the text came out in really odd colors. It wasn't respecting the color style added to the parent td element. To work around that I wrapped the offending merge tags with span elements:
<span style="color: #858585;">*|LIST_ADDRESS|*</span>
Also, I used the LIST_ADDRESS tag instead of the LIST_ADDRESS_HTML tag because the text is a lot simpler and looked better in my footer.
There's a lot of other cool features that the MailChimp template language can do, and I'd be fun to go back and explore them. I think I want a pretty simple and clean template for most communications though. Trying to give the feel that the email is from an actual human and not a canned response from some corporation trying to sell you shit.