We want to make a DNN 9 more secure.
Is it possible and feasible to change the default "portals/0" to "portals/
Would the correct way be to update the Folders.StorageLocation?
What problems would I run into?
It's likely to be cumbersome.
What I would do is export the portal and it's contents, and then create a new portal with the export as a template. You can, I think, also specifiy a name for the root portal.
You may have issues with links in your content that refer to the old root. You may also have problems if you have modules that don't export/import content. So, you'll have to fix that stuff manually. There are modules available to to search/replace within a portal to fix link issues. If you are using portal level skins, you'll need to move those early on -- I think before touching anything that will alter settings.
If you aren't sure what you're doing, ask for some help.
Oh, and you'll probably want to make the portal files all "secure" do obfuscate directory names, some of which may refer to the portal root. And don't put files in the root directory either.