Yes you can go back to crash island by talking to dearo after MM, you have the option to go back and the option to "train" pick go back to crash island and your pure is safe.
70 Cooking
10 fishing
20 firemaking
30 crafting
25 thieving
30 ranged
5 fletch
10 mining
48 agil
Cooks' Assistant
Fishing Contest
Goblin Diplomacy
Demon Slayer
Gertude's Cat
Shadow of the Storm
The Golem
Big Chompy Bird Hunt
tree gnome villiage
the grand tree
monkey madness
Don't do Sir Amik, Lumbridge Sage or Culinomancer