You can certainly just try using the iExplorer demo to mount your iPhone and try using a file utility. The demo lets you mount but has a limit on the amount of data you can transfer before hitting a maximum allowed before buying, though usually disk recovery software won’t be able to see a mounted iPhone with iExplorer since it’s more of a virtual mount. On a Mac, we use OSXFUSE and on a PC, iExplorer uses CBFS (Callback File System) by Eldos. People have reported disk recovery software not “seeing” the mounted device, but you can certainly try. However, iOS also doesn’t have a trash or recycle bin, so once data is deleted, it’s gone (or considered as available disk space until it gets overwritten by new data).
As for renaming files in your Media/Recordings folder, it’s not recommended, but it’s not going to “hose” your iPhone. It’ll just make any of those files orphaned from the database where it belongs, and they won’t be able to be accesses in the Voice Memos app and will just take up space on your iPhone.