Best way to subscribe to podcast back-catalogs?

Every now and then I come across a limited-run podcast that wrapped up ages ago and I want to add it to my feed. I don't want to manually click through the old episodes one by one, I want to subscribe to it as if it were being published in realtime. Are there any tools that can help me with this?

I think what I'm looking for is some sort of app that republishes an existing RSS feed with a date offset based on whatever recent date you subscribe to it. Even better would be something that lets me specify my own custom drip rate so I can binge through large catalogs at my own pace.

I've been thinking about coding something like this but I don't want to reinvent the wheel if an existing solution is already out there.