How best to automate the defence of a non-colonised system

As far as I know, the AI will only attempt to lay mines/sats etc in a colonized system. If you have no colonies in that system, it won't automatically defend it so you would have to do so manually. Is there not even one moon in that system you could colonize? If so, that is all thats needed.

Why not put some minelayers on repeat orders (load mines from nearest colony, remote launch on the warppoint)

Also good is to send a fleet of SY ships to build some bases.
Make yourself some BSYs which you can put on repeat build, and throw in some giant supply tanks to keep your stuff topped up. (By which I mean a base filled completely with supply/ordnance and maybe some armor to protect against pot shots. Being unarmed the enemy shouldn't shoot at it too much, but they might not have any other targets in range occasionally)

You could even have a SY base which includes cargo bays and a mine layer. Repeat build mines, and launch mines on repeat orders too.
Do one for satellites, and try a fighter base too.

Although that suggestion would be gladly taken up by most it doesn't seem appropriate as a response to the first post given that they said that they wanted to defend the space not the warp points