Ok, so I'm going to answer my own question based on my own experience and view.
Steps:
(1) evaluate where you have a 4year old with superman strength who can get his arm into the innner fender well area or through the hole behind the headlight. If yes you are golden, if you can snake your own arm/hand in there you are golden.
(2) evaluate if you want to take out your battery or batteries, and remove whatever connections you have to the batteries.
(3) face the cold hard fact if you are a zero above...its time to look at the Wheel Well removal, does not have to come all the way out of truck but does have to be fully loose, to allow you to snake your arm/hand up between the wheel-well and the fender lip (coming in from the outiside of the fender. No way I can get my arm/hand into the hole behind the headlight, no way I can get full or enough access from the holes in the fender (engine compartment side) to get into where the wiring harness is (connector) such that I can get it loose.
Passenger side.....take loose all the bolts that hold the inner fender well, including in my case one bolt coming down from the aftermarket battery tray I have. Let wheel well drop or assit it dropping about 4 inches or so, take marker light loose, stick hand/arm between wheel well and fender to disconnect the fender marker light harness and replace. Replace bolts and tighten stuff back up
Driver side...same thing, in my case I have dual batteries but for whatever reason on the driver side there is not a bolt that goes from the battery tray to the fender well.
This is not a crazy job...I was hoping to avoid having to deal with the wheel wells....I found no other option. Both of my front fender marker light assemblies had crumbled to garbage status. When I took the light out...the lens came off, then the black plastic stuff came out in parts both on the outside of the fender and the main body of the assembly. I've posted up some pics for everyone's enjoyment.
The hole behind the front headlights did nothing for me, the inner fender holes were about the same (non-value added). So far nothing broke which was surprising (bolt wise). I did find I need to address an issue with my front marker lights, which is not a major thing, but I might as well do it now.
From my experience, its easy to damage the front fender marker lights, and the rear fender marker lights and the rear brake lights off-road. Noteablly on the right rear for some reason (which I assume is that you can't see that as well as the left). I've hit my right rear fender a few times off road...a couple of times were ($hit happens stuff) once or twice it was ...no way to avoid it....to get through whatever it was...something was going to scrape/hit / impact.
This may help someone else zero in on steps to solve. If the yota people had made the body harness a few inches longer....it would be easy...to replace.
