Syncing without deleting music

Hi, I have just bought a new iPhone 7 (My first smartphone!), my reason was that I was impressed at the 250gb capacity and being an iPod classic user decided it was time to have one less device to carry around with me. So I have been setting it up and have checked the manual manage music in the preferences (my library on my iMac is larger than the capacity of the iPhone so I cannot just 'sync' the whole library and have to select which albums I want), I put maybe 50 albums on and then remembered an old ringtone I have and tried to put that onto the phone (Not straight forward at all, had to create an AAC version and rename it to .m4r) so I placed that into iTunes and there is no way to manually drag it onto the phone like you can with the music, so I go to sync tones and a window pops up telling me it will delete all music, video etc, I'm assuming iTunes can't possibly delete music if the 'manual manage' is checked, but of course I sync the 350kb tone and the 50 albums I had put on were deleted..... anyway, my question is: Is it possible for me to spend whatever a day or so putting 200gb of music onto my phone and still be able to sync other stuff WITHOUT touching the music, I mean everytime I update or maybe want to put an epub on the phone will it delete the music I have spent hours selecting to be on my phone library, or would I be best off putting the music on and then never connecting to iTunes again and just update via wifi or use a non-apple product that allows you to drag and drop?