When I was messing with my Navara (turbodiesel, I had it idling with the crossover pipe off, and there was a definite flow, and reasonable pressure when I blocked my hand over the discharge pipe.
Intercoolers should never be under vacuum, as you wouldn't increase the throttled volume by that much, or expose all those hoses to vacuum.
I'd be worried about creek crossings or the like, as water WILL get in, but a 1/16" hole in the bottom of a bucket will take a long time to empty/fill.
Great thread, and makes a lot of sense.
Could plumb something up with an inline cheapo fuel filter, but probably way more effort than it deserves.