I remember being concerned about the use of their own servers as well (especially as an Australian), as i'd much prefer just to host a local server an invite a couple of friends.
Pretty sure i read that they are planning LAN support in the future.
Yep, here it is: During alpha and beta we will be hosting the servers ourselves. This is to collect crucial data such as logs, warnings, errors, crash reports and analytics which we can use to further improve this mod. LAN play will probably be supported after the beta.
We will be hosting the servers on multiple locations over the majority of the world (yes, including you Australia). You will be able to join friends using an in-game UI to simply either spawn a server or join a friend. All you need is an account on the ST website which can keep track over potential Patreon rewards.
We do not have a server limit, so you will be able to play at any time. Every server will technically support up to 64 players at the same time. Though, we recommend playing with smaller parties of 2-8 people as that is what we tested it on.