Use Remote Play Together to Play Online
You can use Steam's new feature - Remote Play Together - to play "online". The host has to have a decent internet but I know I am getting the game soon to play it this way. I can stream to 3 people without big issues so this game is just for us.
For those who dont know - it allows one person with the game to stream it to others. Those others can use their controllers and the game treats them as if they were plugged into the host's PC. With decent internet it works almost perfectly with minor hiccups.
You can only have one shared keyboard/mouse though. Depends on particular games and how they deal with local multiplayer.
Alternatively, there is a program called Parsec that allows pretty much the same thing. That one is not integrated into Steam though but because of that, it works on literally anything.