Installing the tail lights at first feels a bit like “square peg in round hole”. Indeed, you do have to trim some stuff to make the light fit in the opening and then you have to figure out how to mount it. I thought about this a lot and looked at various other builders’ solutions. In the end, it’s an amalgamation of those or unique – the same thing in this case. So below is the step-by-step of what I did.
Step 1: Cut access holes to change the bulbs

I did a few measurements and found roughly where the rear of each of the bulbs is. I then use a 2 1/4″ hole saw (biggest I had) to make the holes, filing the edges down with a hand file. I verified that my fingers fit through the opening to change the bulbs. At a later point, fender guards will be installed behind these, but there’s a removable opening in them to provide access.
Step 2

With the housing held in place, I stuck a pen in through the access holes and market the outlines of the four mounting holes. In the picture, the top are already drilled. These are much larger than necessary, as I used fender washers on the other side to secure. Getting the lower ones dead-on is much easier – and necessary. You can see where the line is thicker – thats the outline of the lower mounting holes.
Step 3: Drilling out the mounting tabs and installing bolts



The little tabs are meant to use metal screws to hold a screw into them. It may be possible to just drill larger holes in the top of body mounting holes like I did and then use a fender washer + metal screw to hold the housing in. I’m not sure how good the access is for a screwdriver there – it would need to be a hex or allen key bolt.
As you can see from the pics, I mounted a bolt from below. It’s a 1/4 bolt, so I drilled out both sides of the clip at 7/32 and then drilled only the upper clip to 1/4. That gave me material get a thread on the lower part and mount the bolt reasonably firmly. The bottom pic shows the final package.
Finished product

Here you can see the fender washers and lock nuts used for the upper bolts and the lower bolts. I’m pretty happy with this final install being held in place in 4 places. The lower bolts are into threaded plastic, so having the upper ones there as well makes it super rigid.
How long did it take to install the 2 tail lights (incl. all preparation work)? That must have taken hours – even by using those special tools which you had been using. Who has a fitting hole saw at home?