dslater, Just Do It!
Smart film photographers are stockpiling and freezing Velvia 50: I am double Ziplocking the 5 pack boxes of 120 rolls. I am using Nylofume (gas impermeable - antifumigation) bags for others.
I used to just stick the boxes and rolls in the freezer. But After reading this site, I realize that you have to protect against moisture first and foremost.
Believe me, these will be considered Gold in 10 or 15 year's time - most importantly by yourself..