Hello natemac,
Thank you for your post,
I have been looking into this issue for you and I was able to create projects in several locations on multiple hard drives on my mac. However, I think I might know where the problem is. The editor is not expected to work properly when installed to a cloud storage location like dropbox. Although it may run, several of the features are not going to work properly. If you are looking for a source control solution we offer several choices. I am including a link to a tutorial on how to set up perforce (our preferred source control method internally)
I also am including a link to a solution that a user found to allow them to set up dropbox as source control, but it seems to only work for windows. perhaps it will give you some good ideas on what needs to happen to make it a possibility, but keep in mind that if you create your own source control method, the options for assistance are going to be much more limited than something that is more commonly used such as perforce.
Hopefully this documentation will get you the information that you need to get set up with a proper source control method, and if this is not helpful, let me know and I will be happy to try and find a better solution for you.
Thanks,