I searched and checked the FAQs...

No one seemed to specify if the moisture problem was with just the fronts or the rears. Looking at this write-up it seems that the whole rear assembly doesn't come out like the front:

Installing Clear Side Markers

Is there a trick to getting silicone in there or do they infact come out?

 

There aren't any tricks in getting the silicon on the side markers. I didn't check the write up because the link didn't work for me, but I have done this mod. I just popped out all four side markers using a flat head screw driver and a towel, and put the new, clear, already siliconed side markers in the old one's place.