So it looks like
Undercover Tourist has the 2 day park to park + 1 day ticket for $301.85. Just to be clear that I'm understanding correctly, if I bought the Undercover Tourist tickets, then booked Royal Pacific at the AP rate (when and if becomes available), I could upgrade one ticket to seasonal AP once I'm there (just to get the resort discount), and pay only the difference between the $301.85
UT ticket and the $304.99 (+tax) seasonal AP? It looks like the Seasonal AP doesn't give discounts for food, etc., so we would essentially be upgrading just for the resort discount since we probably won't be able to return for another visit.