I’m happy to help you try to put together an IndieWeb-friendly version with Webmentions which work with multiple platforms including WordPress, Known, Grav, etc. You might find some interesting examples and pieces on IndieWeb wiki, particularly their Education page. I’d love to see Matt add his example(s) to that page for others’ future reference. I did a short demonstration of what the current website-to-website space looks like at the recent OERxDomains21 Conference. You can find the short video here on my site. If you go the older route one of the best planet-like sites I’ve seen was http://connectedcourses.net/, which if I recall correctly was built by Alan Levine. If you poke around a bit or ask @cogdog on Twitter, I think there are some details or a recipe somewhere of how he put it together. Chances are reasonably good that people in the #DS106 or #DoOO space have some ideas as well.