^^^ That's a W168, not W169
I have done this recently (last week actually), although I don't have rear doors
You can start by getting a few spare door card clips, and four mirror cover clips, as it is likely you'll need them.
I'm attaching some WIS files, but essentially this is what you have to do:
- Remove the mirror cover
- Remove the access cover
- Remove the back of the pull recess
- Unscrew two T30 bolts
- Remove the retaining clip on the side of the door
- Unclip 8 (or 11 for a coupé version) clips
- Lift the card up carefully, until the door pin is free
- Disconnect the windows switch and the courtesy light plugs
- Unclip the door handle wire hook, and pull it out of the guide, until free
- Remove the door card
The reason I removed mine, was to fit a couple of door handle LED lights:
Let me know, if you want details