Looking to add an extra power port for a 12V cigarette style plug in. Would like to know the best spot to pull it from. Wanting to avoid screwing up any systems/modules.
When I tow my camper I have a rear view camera on the camper, a Garmin GPS, My wife's cell phone, my cell phone, and a USB for our music we like.

 

Would a splitter work for you? Some of them have USB ports as well. I cannot vouch for this unit myself, but perhaps something like:
Your truck, your call obviously - but I would not want to tap into anything on mine unless absolutely necessary.

 

I like that. Splitter that doesn't cause any wiring damage and can be easily removed if needed. Noice!

 

None of that will overload the dash power port, it's rated 10A.

I've got my tablet, RADAR detector and Dash cam attached to my BuiltRight Ind Dash Mount, so I tapped the wires at the back of the dash 12V port and installed three new 12V ports under the Dash Mount.

We typically have our phones connected to the center console port, but at times have a third phone connected to the dual USB adaptor in one of the three 12v ports I added.