Hi jnansley,
Thanks for taking the time to share such detailed comments and feedback about your research and choices … I appreciate it!
Most importantly you are certainly making some great choices … and congratulations on both of your new mattresses
You’ve probably already seen this but there are some DIY suggestions and designs for foundations and for platform beds that were contributed by some of the other forum members in the foundation post here that you can use as a reference. If you decide on one of the platform bed designs then you wouldn’t need a steel bedframe.
The OMF steel bedframe would certainly make a suitable choice and post #10 here has some additional guidelines and options for steel bedframes as well.
Thanks again.
Phoenix