You should adapt to your needs the parameters [font=courier new]writeResourceURL[/font] and [font=courier new]readResourceURL[/font] in SweetHome3DJSApplication initialization.
These parameters and other ones with a URL can be equal to the URLs of your choice to customize the services which manage the storage of homes, resources and preferences. These services may store resources in a folder different from [font=courier new]userResources[/font] in the web space of the server. It may depend on the logged user and use a database for example.
This is the case for Sweet Home 3D Online version. If you look at the source code of [font=courier new]SweetHome3DJSOnline.jsp[/font] displayed when you edit a home in the Online version, you'll see that [font=courier new]SweetHome3DJSOnlineApplication[/font], a subclass of [font=courier new]SweetHome3DJSApplication[/font], is initialized with parameters different from the version in SweetHome3DJS public code.

Thanks for proposing a docker image, but I prefer not to make the delivery of Sweet Home 3D new versions more complex at this time. Creating this image could be automated in a script but the result must always be checked manually, and I don't want to make the delivery checking time last longer. But feel free to program it in your project.