I'm not sure I understand.
There are 3 Task Statuses.
My idea was to take for example 4 custom records and map them all to the first task status, then take for example 7 other custom records and map them all to the second task status, and then for example map 4 other custom records to the third task status.
Then you have the native task status, and your custom ones. But I do see a problem now where what do you do when the system sets the native task status. Which custom status should that go to? I adds more than one layer of complication.
Thinking it through a bit more, I think it's better not to try to map them together, and just have an additional field that tells you more information about the Task than the native one does, and leave the native one alone. That additional one, since it's not mapping to anything, can just be of a custom list rather than custom records.