Hi
@88mick88 I had to do similar when installing a towbar on a 2017 PD (don't laugh technically I can pull the skin off a bowl of custard now!). I went the same route your alluding (drivers side, down low along the plastic trim that is between the doors and floor carpet).
Gawd it wasn't fun I will tell you that. Tips? Umm go slow, ideally get yourself a proper trim removal kit, watch some Youtube tuts on removing common plastic auto trims, once you get a few bits off you'll get the idea of where to attack and when you're prying in the right or wrong place.
I found it handy to have a piece of strongish wire with a hook bent in the end of it that you can use to feed back through holes, connect the wires to and pull through very tricky sections. I know when I went through the hatchback section do the rear seats I needed this and also from the rear to front seat sections.
Sometimes worth using silicone spray/lube on the cable. Have a good flash night or head lamp. Dont yank or force stuff, if it's not coming out easy - take a lil extra time to relook at it, as you are likely coming at it from the wrong way/technique.
I didn't have to lift out the read seat - I went around the outside of the rear seats, behind the wall trim thats up at head level - its easy to remove - like I said thats in the hatchback PD though. Might be different for you. The advantage I had was it was an official Hyundai kit - so came with decent instructions, not sure if yours is this or a generic but all the trim will come off, wires and cables can be tucked into any number of places, proper tools and lube will help a lot as if its for power etc you don't want to accidently cut them or have up against metal screws etc that might cut into them and cause a short/possible fire.