I've been thinking the same thing. The tower has three pins on two levels connecting it, from what I've seen in the instructions. I'm not sure if that's enough to support the tower if nothing is under it when it's lifted. I assume so, but I haven't built mine yet. I would hope that there might be another set to rectify this and really hit Jabba's Palace out of the park. Something like the droid dungeon that C-3PO and R2-D2 were taken to, and maybe a cell on top of that for Chewbacca or some random alien prisoner mini-fig we don't know that we want yet. However, looking at the pictures of the Rancor Pit, it doesn't look like there are any plans for another expansion in that area. I guess the standard answer of "you can always add something if you want" would apply here, and I agree that the combination of these sets might look a little odd when it's completed.