I really like in the second picture that in the foreground the additional detail appears to look like “runoff” impressions on the ground.
I’ve got no solution, model wise in mind for your plight, but I’m thinking picture wise with a more severe difference like in the first pic when using your landscape, you might consider a more natural balance of foreground and background as a solution if nothing else works. Maybe the balance can come from a “haze” like that found in real life environments, where the lighter background would lose some detail, but look more believable hand-in-hand with the foreground.
For DS there’s the “Atmospheric Effects Cameras for DAZ Studio”, or maybe a highly transparent fog from the “Fog Deluxe” line might work if you have them and want to experiment with that look. I’m not into DS4 yet, so I don’t know specifically if those work in it.
The only other thing I can think of that might propose a more balanced look is one of those skies that produces a sharper and lighter background i.e. those found in scenes where the clouds are creating shadows on the ground and the background is a lit area while the foreground is shadowed due to that, making ground reacting to sky as seen in true to life scenarios. That one is probably tricky, though. But if you have Bryce, it creates some beautiful skies and can be done to match your camera angle of the scene once you’re set with that. I like to use Bryce often to create the skies and scenes to bring in as the background for renders in DS. You might even find that you can get that effect wholly using Bryce altogether to render the scene, where you’d probably get a true reacting scene from light and shadow in that program. Throwing in some slight God-rays in post with the DS render might clench the deal if you go with using a coordinating sky background in DS. Even some near transparent streaks simulating light in post that are less extreme might do.
Not much, but just a thought. Like I was saying, no help for the model itself, but simply some possible solutions when using it. That being said, if it works great in Bryce or Carrara and such, those could be the recommended programs for the model itself if you’re intending to release it as a product. Using it in DS would simply be working outside the box, where many people like to do that.