I haven't personally checked S&S configuration for this lens yet (just because I don't own one yet).
But from what I hear here and from friends it seems that Sea&Sea's is really the best configuration.
It is to be used with the smaller SXER isn't it???
Note: In 10y shooting S&S, so far I have only seen less than 5 official port configurations where I would rather want to use something different than recommended...
Anything can and should be tested... but from the lens size seems like Sea&Sea's configuration is absolutely right and using it with a ER40 which is 20mm longer than the SXER might get the lens too much inside the dome, and get some vignetting from the dome/ER40. If that is not the case you might get unacceptable loss of quality from the center to the border of your pictures, which should be more strong at the wider focal lengths (closer to 10mm).
Good luck!