If you're not using them already: Enable Runtime Virtual Textures in @UnrealEngine to have your foliage/environment sample the landscape beneath it to nicely blend and remove asset seams. It's really only a little bit of work to do it! Let's check out how.
Step one: Enable Virtual Textures in your Project Settings. Restart Editor. Important step. 
Step two: In your Content Browser create two Runtime Virtual Textures (Under Materials and Textures) and call one Environment and one EnvironmentHeight. Set the Height RVT to "World Height" under content. I also increased the quality of my Environment RVT to 10.
Step Three: In your Landscape Material create a Runtime Virtual Texture Output and get the values you want to save off to a separate runtime virtual texture but ALSO get the B channel of the World Position (using a component mask) and plug that in too. The B channel is height.
Step Four: Blend them together in the material of your asset! Here's how I did it on the default Quixel Asset. I would *strongly* recommend using the Material Attributes workflow so it's just a single pin. The top Sample is the Environment RVT and the bottom is the Height RVT.
Step Five: We're almost there! Create TWO Runtime Virtual Texture volumes around your map and set them to your two Virtual Textures. There's a nice little "Source Actor" option that will automatically copy in your Landscape location and size and just make it that size.
Step Six: Click on your Landscape and tell it to save to the 2 RVTs and set "Virtual Texture Num LODs" to something like 3. This is better for your height sample as it gives it more detail.
Any other assets that you click on and add to the runtime Virtual Texture will automatically be included in the RVT too which can also be useful for rivers and such. Once it's done it's SUPER easy to add it to more assets in the world. Good luck!
As a bonus: If you want to have the landscape access it's own RVT to reduce overall pixel cost you can, however this does have it's own quality drawbacks and you may want to still do cliff blending and such outside of the RVT. Have fun!
