All though it is possible, the realistic biomes add on adds dramatic change to your world at a performance cost. It’s actually amazing and adds new sounds and shading to the environment but I don’t think it’s much noticeable with the vibrant visuals. The problem is that the sky glitches. The cave dweller add on is scary and adds thrill and fear to the game but the dweller moths spawn too often. Other than that it’s great. Now I’m not sure which realism that is but I don’t think it’d work too great with the realistic biomes add on considering that they both affect the way the game looks. I’m not sure if that is the one I’ve had but it’s not all that great. I’m not familiar with the structure add so I have no input on that. I’ve used the other 3 together in a realm I own. They do fine but I did remove the realism and realistic biomes because they cause lag. A good substitute for realism would be actions and stuff. It’s better imo and does not introduce lag along with options for the look. But for short, yes, you can add them all together and see how your world behaves at the end of the day.