As for the trimming, check out my 2nd pic of this post here: Spring A/V upgrade project
. You can see the trimming I did. It's not huge. I used a dremel with a sanding bit on it. Used a shopvac and a wet towel to pick up the shavings.
For the GPS antenna, I've put together an adapter that will let me take the yellow SAT antenna cable from Jeep into both the GPS and SiriusXM plugs on my aftermarket nav unit/SiriusXM tuner. So I'm using the Jeep's SAT antenna. Pics of that to come!!