2nd A/C (Front BR) Selection

[WTP-GC]

We're fixing to buy our 2nd A/C for installation in the front bedroom. Before anyone jumps to conclusions, our unit is 50A and pre-wired for the installation of a "ducted" unit in the front.

We want to sanity-check this before pulling the trigger because the online information doesn't just come out and say what we need to hear.

Here is the model info that we intend on purchasing:
(note that we've selected the 15K BTU and heat pump model simply because the price difference isn't significant)

Unit Model #47004B879 clicky

OR Model #45004-8792 clicky

Ceiling Assembly Model #8430A635 clicky

The question that I can't seem to find an answer to:
When it says "lateral" duct, I assume this refers to the ducts traveling side-to-side of the RV. There is an option for "center" which I assume means end-to-end (length-wise) direction. I think my logic is right, but I just want to confirm.

FYI, we've chosen this model (Mach 8 Plus or Mach 10) because we think its quieter (inside of RV) and more efficient than the Dometic Penguin II. We want to stick with low profile.

Thoughts on this approach...or any better advice? Does anyone see anything wrong with the model number and selections above?