The strategy below is hardly optimal, but it's funny as heck in a masochistic way. 

Idea:

1.  Colonize 100-150 planets with super-breeder and Torian technology.  Build some farms and get the planets to about 18 bil pop.  Don't bother with defenses.  Quantity has a quality of its own.  

2.  Max out econ with governments/custom points/federalism.

3.  Build industrial plans.

4.  Use industrial plants to build constructors non-stop.

5.  Spam protected influence starbases and watch the AI suicide fighters into them.  

6.  Make peace.

7.  Build more influence starbases and convert them.

8.  Win.

The key idea is this:

If you can manage to get that economy up, you can build 30 constructors or more a turn.  Since each AI who is at war with you can only kill about 5-7 constructors a turn at maximum, some of the constructors will get through and you eventually win through sheer numbers of protected influential starbases in enemy territory.