I have a yet-to-be-tested hypothesis that stealth is not about keeping your roof uncluttered but, rather, about the type and style of things you clutter it with. If you want a work van to look like a work van, don't put RV or other consumer-ish things (like a Yakima box or satellite dish) up there.<br><br>So when it comes to vents, maybe we should use industrial looking stuff. Duct vents, vent caps, roof vents for buildings, inverted J-shaped pipes, cargo trailer vents... You get the idea.<br><br>Or we could find ways to make typical RV vents look like something else. Surround it with a louvered box, for example. People with roof racks usually put a sheet of plywood on the rack, so they could attach a couple of boards running lengthwise to the truck underneath the plywood so the vent isn't seen from the sides. Hide it between the rungs of a ladder. <br><br>And here's a wild idea. If you have the big PVC tube thing still on your rack, put a T coupling in the middle, connect it to a flange on the roof (all properly sealed to prevent leakage, of course, put another flange inside with a fan in it, then remove one or both of the end caps on the big ass PVC pipe. If you have the van situated the right way to the prevailing breeze, you might not need the fan.<br><br>Just thinkin'.