Problem solved, lesson learned.
So, I was just reading the other day about problem solving and how it's always best to not over think things and to start with the simplest possible solution FIRST.
When I checked my taillights the other day when connecting the toad ALL FOUR of the stop/tail/turn lights on the back of my RV were non-functional. So, in my mind the most logical thing to cause all 4-lights to go out "at once" was a Fuse. So for a few days I churned around looking for the right fuse and the right fuse location. We even cut short visiting a national landmark by about 2-hours so I could unhook the toad and go to the nearest auto parts store to get the correct fuse.
But that had no effect on the issue.
The next thing was the wiring harness where it travels the chassis to the rear of the RV. It was raining for 3 or 4 days so I put off crawling under the RV to check the wiring. I did check it today and no problems were found.
I decided to remove the entire tail light assembly to check it out and it was sealed in place so well I was having trouble getting it removed. So, I took off the tail light lens to find a way to tug on the assembly - HELLO? What's this? The bulb was shattered.
I removed all four of the lenses and sure enough all three of the other bulbs were shattered as well. In post #3 of this thread "rambler guy" told me to check those and he had had the exact same thing happen to him. But noooooo, I had to waste everyone's time, drive 350 miles without taillights on the RV and crawl around under the dashboard, the hood and the RV searching for what I was sure was the problem.
It did look like all the bulbs had shattered due to water and there was a day just before this all started where we drove in pouring rain with the headlights on - which would have heated those lamps up really well and any water on them would have made them shatter.
So, what did we learn here?
1. Don't be a dope
2. Listen to RamblerGuy
3. And ALWAYS start at the easiest solution first
Quick trip the auto parts store and I bought 4 LED replacements for the 2057 bulbs and a tube of exterior sealant. I sealed all 4 of those lenses and I have stop/tail/turn lights again. Oh, and I checked the only working lights, the backup lights, and I sealed those lenses too just for good measure.
Thanks to all that helped and please let me apologize for wasting everyone's time with this trivial non-serious issue. And thanks to RamblerGuy for telling me how to fix this right away.
PS. One last thing - I suggest you remove all of the Clearance lights on the front/top of your cap and seal all of those with silicone... and then do the tail light lenses too. I have now had issues with both of these things during my first 15 months of ownership and clearly, they are not water tight as they should be. Simple dose of prevention there.
2015 Forester 3051S
TOAD: 2016 Lincoln MKX