Windows 2018 Enterprise LTSC (previously LTSB) is not yet released and NO you cannot use the previous SVF file (used for 2016) to make an early 2018 build to test. edit: This post should have been a reply to a pm (wrong browser tab), but I'll leave it 'as is'.
Changing default file association through windows explorer seems to be broken in this build. If I try to set, for example, a jpg file to always open with another program, I right-click and choose "open with", then select the other program, making sure the "always open with..." box is ticked, the file does open with the selected program, but if I then try to open a jpg file by double-clicking on it, it still opens with the program that was previously the default. Same goes with any other file extension. If I can't fix this or find a workaround, then this is a deal-breaker for me and I'll have to skip this build.
I have an iso of the (possibly) timebombed RS5 to run in virtualbox just to see if there are any new update hijackers in this build. Preview builds give me info I need for the script so it's ready when the release goes public. That's what I use the prereleases for. After I inspect the OS for the information I need I delete the virtual machine.