Wouldn't a podping reason update to the RSS/PI_ID be enough to check for the new episodes?
BTW: Wasn't the crawlers using podping for adding new feeds to the database? I've been doing some testing with [1] and doesn't seem to work:
[1] wget -O- "https://hub.podcastindex.org/pubnotify?url=${Feed}&podping
curl -X GET "https://api.podcastindex.org/api/1.0/hub/pubnotify?url=${Feed}"; -H "accept: application/json"