Migrating from AudioBoom

I’ve been podcasting using Audioboo (now Audioboom) since 2011 and supported the service by paying for a podcaster subscription for much of that time. Audioboom introduced a new pricing structure that I can’t sustain so I need to migrate to a new solution.
Using my LAMP server, which has bandwidth capacity for my podcasts, I set up a new subdomain on http://podcast.cullaloe.net and installed podcastgenerator 2.6. I uploaded a selection of episodes over FTP and used the import function in the admin interface (I had to change the timestamp using touch -t yymmddhhmm.ss filename.mp3 for each episode to get them into the right time order) finally editing in the description for each show.
For the most part, my episodes had embedded images in the mp3 file, but where they did not, I thought about having to edit the ID3 tags. I read about a method for avoiding this which includes posting an image (say, 300×300) for each track within the long description field in the admin interface of the new software, but this doesn’t seem to work. There’s a command line way to pull an image into an .mp3 file which sometimes works as an alternative:
ffmpeg -i input.mp3 -i cover.png -map 0:0 -map 1:0 -c copy -id3v2_version 3 -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (Front)" out.mp3
If that doesn’t work, you can just drop an appropriate jpg/png in the images folder of the same name as the episode audio file.
The iTunes podcast feed was easily updated by visiting https://podcastsconnect.apple.com/  and pointing to the new feed. Note that podcast artwork must now be between 1400 x 1400 and 3000 x 3000 pixels, JPG or PNG, in RGB color space, and hosted on a server that allows HTTP head requests. The iTunes podcast updated overnight without any difficulty.
Finally, I emailed audioboom to request they apply a 301 or iTunes <itunes:new-feed-url/> redirect to the old feed (pointing to the new one).