Awesome tutorial, thanks a lot.
In case this helps anyone, as part of the troubleshooting, I had to do another round of audit2allow to fix systemd sleep not being able to access the swapfile:
#============= systemd_sleep_t ==============
allow systemd_sleep_t swapfile_t:dir search;
I just followed step 12. again with that and used a different module name (systemd_sleep). (Not sure if there’s a way to “amend” the SELinux module created previously, which would be nicer, I guess (?), but it works now, so… 
)