Yes, this is one option to work around Dropbox’s limited permission options here. You can create another Dropbox account and link that to Harp Platform. Then, share your application folder with your main Dropbox account and match the directory structure (put it inside harp.io/apps/), and continue using the Harp Platform normally.

As far as I know (correct me if I'm wrong, please!) there's no easy way to "switch" Dropbox accounts on your computer, is there?

This is something you can easily do. By creating a second account and sharing it with your primary account you can essentially create a sand-box.

By sharing with your primary account there is no need to have a second Dropbox client or switch clients.