Alright, I'll put you on the list. Make sure to read the rules if you haven't already.
In terms of canon locations there are two types:
a) locations mentioned in canon from which we know exactly where they are - of these I fear all are assigned already
b) locations mentioned in some way in canon lore, but of which we don't know exactly where they are and not much, if anything, about what was going on there.
Of the latter there is at least one left with some lore attached to it - the island with the Toa fortress where a team of Toa guarded the Makoki Stone. This would be the island of Tenai (name and location by RSG, see map).
I think I have a rough idea that could be used regarding that, but I'll have to check with RSG first...
I'll get back to you about it.
Rules and list in post 1
All Makuta are currently assigned