The link the Chuck sent you is a good place to get a top of the line fuel
filter/water separator set up. Since you have already thought about the
concerns of the plastic bowl set-up, no more needs to be said except that
metal blows are available from Racor as you can see. However, there some
other alternatives. It sounds like you already have filter separators, the
transom mounted spin-ons are usually 10 micron filters/ water separators
that function the same as the spin-on Racor replacement elements. ( am
referring to the Racor elements that will screw on to your existing heads).
The main difference in their functionality is the Racor's ability to be
drained via a pet cock. With your existing spin-ons you can just spin them
off and dump them in a bucket. If you do this, be sure to put the elements
back on ASAP as the rubber gaskets starts to swell quickly once removed
making their refitting a problem.
But what I would be most concerned about is what is causing the water
problem in the first place? Maybe you have an above deck poly tank? if so,
then pay some attention the vent. If it can be closed, then close it while
not underway. If the tank is constantly being splashed with water then
something to deflect the splash, maybe have some vinyl tank covers made or
maybe some simple plywood covers like an inverted box that could also be
used as a seat?. I think with some "looking into" you will find a better
solution than just being able to more conveniently drain a bowl. Anyway, I
don't think better(more expensive) filters are necessarily the answer to the
problem.

--
Ron White
Boat building web address is
www.concentric.net/~knotreel