So, RSS feed mergers won't work like I thought they would. Since a merger of two feeds eliminates/overwrites all the tags iTunes needs in order to publish a podcast, I won't be able to use that method.
The good news: since I give iTunes the Feedburner URL (instead of the source RSS URL), once I swap feeds everyone currently subscribed to Bakacast will automatically get the new episodes. There will be no effort required on your part to keep up with the new stuff.
The bad news: all the old, Libsyn-hosted content will disappear from the iTunes feed. If you ever want to listen to older episodes, you can use the media player or directly download links available at Project Haruhi; also, I will also provide the URL for the old Libsyn RSS that you can manually add to whatever podcast software you use (like iTunes or Pocket Casts).