Good news!
You're gonna have 57 characters to work with instead of 19.
... Provided I can find an empty bank of ROM that is 57 x (# of item descriptions needed) bytes long, anyway.

So there definitely isn't an empty bank that is 3600 bytes long, which is what would be needed to accommodate 60 descriptions using the method I had originally planned.
But I did discover that the method by which the messages are indexed is much simpler than I had originally anticipated, so unless you make sixty descriptions that literally use 57 characters each, a bank that large won't be necessary.
What you should do is, assign the descriptions as planned, then practice-write them out to determine how many characters will be used (still using 19 characters per line, but up to three lines per description), then add 3x(number of descriptions) to that total. That will be the size of the empty bank I'll need to use for this little project.
So, for example, if you end up needing 40 unique descriptions, and altogether (including spaces) those descriptions take up 2000 characters, the size of the empty bank I'd need would be 2120 bytes. That's still a lot, but there is at least one empty bank in ROM that size (I checked).
Did that all make sense?