Well let me throw a different point of view at you from the performance world..
Your pickup's can pick up all sorts of debris. There are some kinda thorny plants in fresh water that will actually destroy a water impeller in no time flat. It's recomended in I/O boats that you change the impeller every season. I'm not sure if it's the same in inboards, but honestly I can't see it being much different.
We all love our boats regardless of their different breeds. The motor in our boats is arguably the most expensive thing in the boat!!
So to go along with my "fuel seperator" advice, plumb one of these bad boys up in your water system, and your problems will be solved.
They catch any large debris that can ruin an impeller, etc.. Plus you can just look down in them and visually make sure that your motor is getting water! http://www.rexmar.com/page173.html http://www.stainlessmarine.com/strainer4.html
They seem kind pricey, but both I put up are top of the line, add a nice appearance, and give you peace of mind on your motor. Cheap insurance if you ask me.