stillb-
Some of the members (elsewhere if not here) have fitted their own prefiltering or dedicated polishing systems into their fuel systems, using day tanks, gravity feed, or an
electric pump with valves for "polishing mode" to the tank without running the
engine. The idea is out there & folks are doing it!
Then again, there's always the "baja filter", i.e. a coffee can or pipe fitting with several filters & water absorbent material fitted onto a filter, and used in between the fuel filler and whatever fuel is being poured into the
boat. They're even available commercially now from West and all, I think that's what talbot is describing. If nothing else--you can see right away what is being
sold to you, and stop the gross contamination before it gets into the
boat.
The downside of course is if you are using something like paper toweling in it, disposing of the mess (& fumes) properly before casting off.