Works with druids of all races.
It's very simple, you might even say it's common sense.
1. Enter the river next to old Tarren Mill.
2. Shapeshift into Aquatic Form.
3. Exit Aquatic Form
The disguise will not resume when you leave Aquatic Form. However, it will if you enter and leave another shapeshift form.
(Repost claims must be backed with a thread dated prior to this one.)