I just run a mercriuser style filter seperator type. You can get them at any marine store. It uses a spin-off cartridge like an oil filter, and replacements are available from Napa. I just spinn mine off every so often and dump it, checking for water. Hopefully often enough that it does not fill up with water.
Sometimes I do get water out of it.
If it's wet, I replace it.
Some run racor type filter seperators. They are expensive, but the best.
Others may know of better options than I do.