As is typically the case on the Tuesday after a Windows 10 Insider Preview release in the Fast ring, Microsoft has released a new Windows 10 SDK Insider Preview. The build number coincides with the current Fast ring release, which is build 18298.
As usual, Microsoft hasn't published a changelog alongside of this release. We'll probably see one later on today, if not tomorrow. It's unclear as to why the firm has so much trouble with publishing the blog post at the same time as a release, but we should probably be used to it by now.
You should be able to use today's SDK alongside of other SDKs, which means that you can run it in a production environment, as long as you target an earlier version of Windows 10 before you submit it to the Store. It should also work on both Insider Preview builds and supported versions of the OS.
If you want to download Windows 10 SDK Insider Preview build 18298, you can find it here.