After reading all the aspects sounds like the only way around getting any kind of water in the fuel would be going with a fully closed system. I cant picture a way other than what Chip touched on with the check valve arrangement, but hard to figure out the schematic for me if Im using a Perry system. Now its turning to a fuel system problem for me...lol..duh. I'll just go ahead and state what I would like to see for a system and go from there.

Here is what my initial intention was with the fuel system before I got sidetracked with my ideas: VP-30 Perry Pump, Check Valve, T Fitting, Third Channel mixure valve, Fuel Filter, Dubro quick-fill port, and a SLEC tank. I'm going to work on a sketch of the plumbing and post it. Its the vented tank thats my hangup due to water spoiling a tank of fuel or others to follow if it doesnt get sucked out.