After looking at the other microspace systems, and deeming them all too complex to remember (and too long to bother to read) I decided to make a simple system, following the original Brikwars rules as much as possible. In fact there are only three rule changes in my system.
Ships with a Size of 2 or more can pivot 45 degrees per turn. Smaller ships can pivot freely.
Weapons on micro ships are small. Guns that are facing the same direction can be counted as a single gun whose Size is the combined Size of its components. Ships carrying fighters or boarding shuttles counts them as a melee weapon.
The Structure Level of a ship must be smaller than its Size. For comparison, a ship with SL 0 is lightly constructed and has no shields (example: X-Wing) while a ship with SL 5 is very sturdily built and heavily shielded (example: Death Star).
Remus: Harry... I'm a werewolf.
Harry: Are you fucking serious?
Remus: Well yes, but I don't see how that applies here.