I like(d) hunting big Wahesh.
I know that a number of players were asking for small Wahesh. I think there is enough space on Planet Toulan (large sea north of the island) for different Wahesh spawns with different maturities.
Nice ideas about a spawn in the sea but due to the mob description: " This rare, immense lake monster is a creature of legends. Many villagers and travelers believe him to be a myth, and those who set out to find him quickly find themselves on a dangerous journey. Known to be directly linked to Nawa sources beneath Al Hawa Lake. The Wahesh emits Nawa energy in sparks, making him highly sought-after by the Nawa-obsessed.!" I wouldn't make a mess in the good old MA style spawning mob randomly without any storyline.
Since the Wahesh is a lake monster I would make 2 spawns high and low maturities in 2 sections of the lake or make a new spawn on the other side of the dam.
About the large sea area would be lovely to see a new brand mob