Trailer Wiring

I've put a Class 1 receiver on my 2011 EX35 for a bike rack and towing a light weight utility trailer. I've wiring other cars for trailer lights so this is not new to me, I need access to both lights wiring and I figured out how to remove the tail lights. The part that is a mystery to my is how to access the inside panels to run the wiring from the drivers side light to the passenger side light. I know the inside panels must be removable but I have found any place obvious to start the removal. Mainly, I don't want to break anything. The past cars I have done have access ports, the EX35 does not. Guidance would be greatly appreciated.