From my continued reading, it appears that what I wanted to do is not possible.
I ended up making a design choice of having a 4 row table on the second Master page. The user's data from sfmSTO will copy to the second (and subsequent pages). If the user only chooses to create 2 STOs, there will still be 2 empty rows on the second page. If the user chooses to create more than 4 STOs, only the first 4 of them will be displayed on pages 2+. Not ideal, but certainly workable.