Thanks very much for responding, jhan, but I've sorted this out. When I looked earlier, I completely missed a dmesg entry having to do with mounting disk partitions, which ultimately led me to the solution.
I have a pre-existing Solus installation on this machine. By way of preparation, I went ahead and used GParted to create my Funtoo partitions in some unused disk space. I also added a data partition at this time, which could be shared between Solus and Funtoo. At the conclusion of the partitioning and formatting, I ran $ sudo blkid from Solus and copy/pasted the output, so that I would have the UUID of the data partition (and indeed all of the disk partitions), when installing Funtoo.
When I edited Funtoo's fstab file, I used some of Solus' partition mounting conventions, such as errors=remount-ro. And indeed, I had an error. So, it wasn't just the /etc/portage/make.profile/parent file that was unwritable, but the entire disk! Only ... parent was the first and only file that I tried to edit (through EPRO) today.
So, long story short, tidying up my fstab file has allowed me to set the flavor for Funtoo.
Thanks again for responding so quickly.
Cheers!
