Can rough roads create a suction from the water tank vent?

Thanks all for the responses.

I think that I can visualize water sloshing out, but probably not siphoning... although some of those corners were pretty impressive just south of Yachats. My wife gave me a side glance or two.

I like the idea of a plug or valve in the vent tube while underway. Are there any issues with pressurization while using the pump?