I now understand what you mean about modifying the podcast "on the phone" by using the PC iTunes sidebar section. I've used it, just not to modify the contents.
I also don't automatically sync.
First I download the new podcast(s) to iTunes, then modify the start time, lyrics section, and add the individual artwork for that session.
Then I sync to both my iPhone and my iPad.
On my iPad I can also study the lesson contents with PlecoDict (language dictionary).
A modified version of your method for me would be simply to change the Media Type while I'm doing the other changes. Wouldn't take but another second.
If I can then create/modify a playlist for the podcasts (done it before) and sync the playlist, I'd be fine with that as long as the playlist makes it over to the iPhone. Dragging the new podcast(s) to an existing playlist would also be easy; given what I've already been doing to prep my podcasts.
I want to sync and have the computer and iPhone consistent. I also have an older iPhone and iPad that I sync to this same library, and I need them to all have the same contents. My podcasts are language lessons, and I use them on both iPhone and iPad, keeping their played status uptodate depending on which device played it latest.
Thanks for the suggestion. I'll try out my version.