Under Seat Security Safe for 2005 Moons & Tunes Vibe?

[vibedrive]

Looking for a security safe to keep some of my valuables in while driving through Mexico, such as Passport, and $$. A friend recommended an Amazon product, but it does not seem to fit my Vibe. There seems to be stereo amps or pre-amps under each seat. Here's what I'm looking for:
http://www.amazon.com/Bestop-42641-01-U ... d_ys_iyr16" onclick="window.open(this.href);return false;

[Derf]

Correct, their is a factory amplifier under the front Passenger seat. Their is however space in the back hatch area in the side compartments around the rear wheel wells