I asked the same question over on StackOverflow, but thought I might get more visibility here.
I've done some searching, and I can find examples of people setting up virtual directories/apps under a DNN installation, but I can't find how one would limit a virtual app to a single portal. This is key for us, as we can't have these apps showing up under the wrong site.
Is this a supported pattern with DNN? Or should I be looking at some other solution, such as moving the apps into subdomains? I know there's the option of rewriting some of this as modules, but one or two of the apps are complex enough that I'd prefer to avoid that route.