I was familiarizing myself with the CK with hopes of claiming this one, but since you've already claimed it I'll just share my ideas and you can use them or ignore them as you wish.  

First up, there's some boats leaning at the end of the first hallway that these smugglers use to transport goods up and down the river system.  You might want to talk to the landscapers about replacing the entry door with a Skyrim-style cave teleport to make it easier to get the boats in and out.  That door also really sticks out and makes the presence of people inside very obvious (it can be seen from the road between Pelagiad and Seyda Neen!), whereas a simple cave might just be a grotto filled with mudcrabs.  Looks much more inconspicuous.  I was also thinking of placing a door and dismantled door frame inside the cave someplace near the boats, to suggest that there was a door but the smugglers removed it.  

Second, there should be some handcarts for moving all those crates around.  They're stored pretty far from the boats, and that's a long way to carry those crates back and forth.  

The second room is the only one with substantial dry, solid ground, so unless you're redesigning the cave, it's the best option for a cooking fire.  It's also home to a random rat or shalk.  Maybe there should be bear traps to catch the pests?  

There's a Fighter's Guild quest to wipe out the Verethi Gang, and all the dialogue for the quest vaguely refers to an "influential client."  (Just in case you've never played Morrowind, the Fighter's Guild is corrupt and controlled by the Camonna Tong, but the public is largely unaware, so the Guild is used to eliminate rival gangs while appearing to help law enforcement.)  The gang is smuggling large quantities of generic random goods up and down the same river system that the Dren plantation uses to transport moonsugar (they even have a dockyard).  Seems to me the extra traffic on the river has ruffled some feathers, and these guys aren't paying a cut of their business to the Camonna Tong.  What's their business model?  Are they smuggling stolen goods?  Are they part of a network smuggling goods across the Inner Sea with cheaper overhead than the import dues imposed by the East Empire Company?  Are they even making enough money to pay off the Tong?  Have they just found a moonsugar supplier not associated with the Tong (or at least willing to work with others for a better price) and started to branch out into smuggling a more profitable product, but placing themselves in more direct competition with the Tong?  If so, Dovres will no doubt want to keep a close eye on the new, high-value merchandise.  Some questions to consider.  

Also, their healer Penald is the least experienced member of the team, just in case you can find some way to make use of it.

Hey, I am currently working on Adanumuran and haven't started here yet. If you want to do it Temp Man no worries. Please un claim me from this one. I'll continue on Adanumuran. =) Started a new job recently so less time than initially thought.