2015 international prostar batteries access? Remove skirts?

I have a 2014 with full skirts. I found it a whole lot easier to unhook the batteries, turn them sideways and they will come out.
The first one out and the last one in can be a pain. Wear gloves. The hole is just big enough to fit the batteries through sideways. Use a tarp strap to hold the battery door up, as to not get in the way.

 

Mine are too. It's tight. If you want to take the skirts off you'll want a battery powered impact with a 3/8's adapter, 7/16 socket, 7/16 wrench and a 40mm torx. A set of ramps to pull the truck up on.
Pull the aluminum steps off with the 40mm torx, pull the trim off under the doors, start taking nuts snd bolts off on top and bottom of fairing.
Your first time will probably take a couple hours to get apart.
These are a pain in the butt. When I bought the truck I was hoping they would be like a Volvo. Nooope, lol

 

The skirts do have to come off. They will not fit through that little access flap. Newer trucks require removing the steps only. I believe yours will require removing the steps, then removing the plastic skinny side trim piece just below the top step, there are bolts in behind. Only the main bolts have to be removed to remove the whole skirt section. There are two more main bolts under the bottom step. I believe the hood latch has to be unbolted too along with two small screws at the front as well.