I ended up paying for goodsync. The client runs locally but it only needs temporary local storage (if that). I tested a lot of programs, looking for one that preserved the created date. Even the native OneDrive client no longer seems to preserve them. OneDrive is a little odd. There's a created date on the cloud and there's a FileSystemInfo facet that preserves the original created date (with the right client).
The biggest asterisk is that iCloud doesn't have a place for local data so the client has to scan it every time. If your goal is to remove most of the data (the only way to clear space on your phone, this shouldn't be a big deal.