Big job is a relative term. You do not have to remove the whole interior but certainly some of it depending on where you want the solar controller and where your batteries are. Basically, you're tapping some holes in the roof of the PH or fabbing a rack from the holes for the existing lifting mechanism. This is my preference, plenty of holes and bolts up there already to attach panels. Then you'll need to bring wires down from the corner of the PH interior to the inside of the van walls by routing them around and under the trim for your PH, meaning the lip around the hole in the roof of your van. From there you're just routing two 10 gauge wires to your solar controller and then to the batteries or tapping in to your exisiting DC power at some appliance, but preferrably straight to the batteries.
I've done this job about 5 times I guess. I would charge several hundred for the work and then the price of parts (whatever panels, controller, etc. you want) on top of that but I cannot personally help you. Way too busy with work even if you were close to me.
Short story, you're probably looking at $1k installed and the van would need to be with the installer for a day or two.
In this #vanlife world I would think finding someone to do this would be pretty easy. Start with where you're located and many here can probably suggest someone.