Syncing between Mac and iOS - Dropbox workaround

I have OO 5 and work in a business in which shared documents are stored in Dropbox. Now that OO has its new file format, I can put shared outlines into a Dropbox folder and others can open them. BUT I also work on an iPad (and sometimes my iPhone). I can get my Dropbox OO5 outline to open on the iPad by using the “Open In” function. I can then edit or add or whatever. But I can’t make the trip back easily. I guess I could e-mail it to myself, maybe as on OMPL file, and then save that to Dropbox when next I’m on my Mac, but that is the opposite of friction-free. I wonder if anyone has come up with some sort of way of making this round-trip less cumbersome. It doesn’t help that there seems not to be a way to save an iOS OO file directly to Dropbox.
Any ideas?