Hi, I've been playing Sins with a few friends for a few years now (since before Entrenchment!), and we've kinda tailored certain aspects of the game to our liking over the years. The only mod I am currently using is Distant Stars (for Diplomacy).
I don't really do a lot of modding, mostly just tweaking (in-game strings, music, portraits, etc.), and now I've run into something I don't think I can easily tweak.
Currently, when setting a game's options, the "Fleet Size" option changes the default fleet capacity by 25%, i.e. 25% increase for larger fleet -- 25% decrease for smaller fleets. To give Starbases and Capital ships a bit more punch, I'd like to try playing with 50% smaller fleet sizes. I just always feel that by end-game I have more ships than I really know what to do with!
I was hoping I could get some advice on where to start making the necessary changes for the additional decrease. I haven't really done at lot of hands on modding in the past, so I thought maybe someone on the forums could point me in the right direction. Thanks for taking the time to help out! 
-M