Jim - The differences in light measuring ability between your 5d2, a light meter, or even your iPhone.. for the purposes of landscape photography.. are so close that what really matters is you:
1. Choose one
2. Learn HOW it works
3. Understand HOW different light scenarios produce different readings
4. Practice with it. Practice with it. Practice with it.
Consistency is key and 1-4 above results in consistency. Especially #4.
A histogram, spot metering, etc.. help you become consistent, to the margins of error inherent in that device, faster. But if you don't learn how it works, how it produces different readings for your style of photography, and if you don't practice with it over and over and over again.. then you won't reach that next level of consistency.
After holding many photography workshops I've come to realize the most common question a student wants the answer to. It's not about equipment, or focal lengths, or anything to do with what you'd think. The number one question is how to achieve great results without putting in the hours of practice. And most of the time they don't realize they're asking this question.
There is a tendency to think that because anyone can "turn on" a camera and make captures with it.. that it must be easy. This is one reason we have so many self-taught bargain-rate wedding and portrait photographers out there. Virtually anyone can pick up a modern camera and with enough captured frames can come up with something resembling a wedding. So to earn extra bucks or whatever they become instant wedding photographers.. they think it's the easiest type of photography accomplished by anyone with a green box on their program mode dial. I might take some flak for this, but I personally think weddings are the most difficult type of photography I know of. Wedding are when all your exposure skills come into play ( you can never tell what light/direction/etc you'll get), your lighting skills (again, you can never tell what you'll need so you'd better be prepared and accomplished with many types/styles), focusing (often fast moving), low light (often many low light elements), portrait skills (oodles of portraits with all the factors above), timing, organization, and of course people skills.. The better you are at all these things, the better your weddings will be overall. But the way to get better at all these skills? Practice them. And then practice some more. Then do it again.
You're already on the right track. You're scheduled to go out and shoot. You're putting yourself behind the camera aiming at landscapes. And you're learning your gear.
Have a great time on your trip.