Just remember, putting an A/C combo DC USB plug is still using A/C to make that USB port hot. To have it HOT while boondocking you will still need an inverter or generator.
I would suggest, if you are considering off grid camping, to run DC wiring separately from your DC panel or battery system with a fuse and and install separate USB outlets.
My 2 cents.
Chris & Donna
2014 Voltage Epic 3990, 600AH Lifeblue, 1895W Solar, 3K Magnum w/AGS, 3X Micro-Air ES
2018 RAM 3500 Laramie Sport Crew Cab 6.7 Cummins, AISIN 4X4 DRW 4.10 Long Bed Dually 2004 Sportster 1200c