I started prototyping something very similar to this but was going for a singleplayer thing to start where you control one ship at a time. The hard parts I bumped into were: 1) the scale of space doesn't play nice with Unity C# floats 2) the scale of space doesn't play nice with the player's time 3) Switching to a language I'm comfortable with that solves both 1 & 2 means I would have to go back to school to learn how to write a physics & collision resolution engine or learn a new engine & language.
In any case good luck on your project because the idea you have is basically the same as mine and has been a dream game of mine for many years.