Our toe brace is designed for the second lessor toe since that is predominantly the most common toe to develop a hammer toe.
However, you can shorten it by cutting of the excess and use it on your forth toe. The loop will protect your top knuckle from the corn you mentioned was developing.
There are double toe braces available but I can't remember seeing one specifically designed for the forth toe.
Our toe brace is the only one I know of which also protects from corn development so I think you should give it a try.
