So short of a better solution, here is the hacky way that I was able to kinda get DCV 2017 working in full screen across 2 of my 3 monitors.
1) Open DCV connection.
2) In settings > Display Resolution, set to Adapt automatically
3) Put the viewer in Full Screen mode across All monitors
4) Inside of the Linux client, open the display settings
a. It should show 3 virtual monitors
5) Click on one of the side monitors and uncheck “Use this display” (or other similar option)
6) Click to keep changes.
7) While still in full screen mode, set the display resolution to the current resolution (3810x1080 for me). This turns off auto adaption of screen resolution.
Exit full screen mode
9) Go back into full screen mode on a single monitor
10) Open a second DCV session of the same connection
11) Set it to full screen on a single monitor on the other monitor.
12) There will be scroll bars on the bottom of the two viewers, scroll one all the way to the right and one all the way to the left.
13) And you are done. You can kind of drag things between the two windows now.
If someone has a better solution, I'd like to hear it.