Trouble moving self-made tones to 4s

I have a pretty difficult situation that I cannot find a solution to. I lost my self-made tones when I upgraded to iOS 8, and I cannot get them back onto my phone. They appear and play in my iTunes Tones folder, but will not drag to the phone. I cannot sync the phone to this iTunes, as all my music is on another computer and this will erase all that media on my phone. I cannot sync and then restore my music/media from the other computer as it is a much older model and no longer recognizes my iPhone since the iOS 8 upgrade.

Is there any other way to get my self-made .M4r files onto my phone besides syncing and erasing (and permanently losing) all my other media? Apple, why can't this be made a simple drag-and-drop like it used to be? Thanks in advance to anyone who can help.

I have an iPhone 4s running iOS 8.3, and iTunes version 12.2.1.