According to the shop manual, Section 76-42, you drop the cover underneth the left side center floor plate to reach the valve. I've got it on good authority from another Eurovan owner that's the only way, pain that it is.
Besides the main LP valve, be sure and shut your fridge down per the owner's manual. Vanagons have a 2nd shut-off at the fridge, return the thermostat to off and leave the electrical 3-way switch at LP. Sound like your Euro?
[This message has been edited by Capt. Mike (edited 08-05-2000).]