Keep in mind that this method is only accurate when the missing characters are all at the end since the farther away they get from the end, the bigger the range is going to be compared to the actual range of missing characters.
I know, but I have prepared a version of Kangaroo which works with given stride - just to be able to solve WIFs, preferably with missing beginning.
https://bitcointalk.org/index.php?topic=5315607.msg56298967#msg56298967