TB -
Great time ya had! I see you found one of my secret places for a quick cheap lunch too!
Cali - ya gots lots on your plate, but it's easy. Don't stress. It will all work out. You can combine HC/SRA and a BBQ all in one. See? Your plate just got less full - oh that just gives you more time to explore
If it were me, I'd save Xuna for a return trip, spend sometime inland and visit it then. Replace it with Lamanai ( My #1 preference) or Altun Ha.
You should be able to combine the caving/zoo/zip all in one adventure packed day as well.
All can be easily arranged once you get on island.