I'm going to be adding some things I found on a post from John Judnich.
JohnJ wrote:These expansion packs are free map and tank add-ons to BattleTanks II. If you are interested in creating your own tanks or maps for BattleTanks II, read “Expanding BattleTanks II“.
If you created an add-on tank or map for BattleTanks II, feel free to click the “Edit” button at the bottom of this page and add it to the appropriate list below.
I will be adding them into the addons section, so keep an eye out.