Dear Tom I like to add a couple of things about 4x5:
I have a mono rail for the studio and lately a wooden field camera to make things a bit easier on me.
That much for not more than one 4x5 camera....

There are pro's and con's to both the mono rail and the field:

I love mono rails for their ease of use, its full movements both front and back and what is important in the studio: a focussing back.
They are heavier than most fields but I used a heavy Sinar P2 in the field for over 20 years photographing architecture.

I love my Shen Hao for its compactness and ample movements, the Shen Hao TZ45-IIB has even focussing with the back standard and exangable bellows (standard bellows and wide-angle or bag bellows)
I have the Shen Hao HZX45-IIA, by the way and am thinking about building a field my self based on the SH.

A Linhof Master Technika is a sturdy walk around field camera, a joy to use and expensive, think about $ 2000,- to $ 3000,- or more used.
Earlier versions can be bought for less.

Having your lenses mounted on Technika plates has the advantage that you can use your lenses on the field and the mono rail, the mono rail will just need an adapter plate for the Technika plates. My Sinar has one.

I agree with the idea of first visiting somebody that has either a mono rail or a field, or even better both and to try these camera's out.

Have fun, and a great trip to South America.