Have you used the rules for building bases and if so how did it go? Did the players end up losing the base to Imperial Assault or keeping it long term?

Which book is that in?

There's some in Lead by Example and also in Special Modifications if I'm not mistaken and they're very... lackluster.

Oh yeah and Desperate Allies - thanks for reminding me LaGouache. These ones are marginally better.

There are some rules for creating a Rebel Base in Desperate Allies (p.87)