It is very hard to trade into Belize with RCI. We have tried several times with no success and were told that it sometimes takes two years. I don't have a clue what I am doing in two years!
As far a Royal Palms goes there are a several units that are time share, the rest are privately owned condos. I love staying at Royal Palm, but you are right it is not as spiffy as the nicer RCI resorts.