Set the default window width to 1/4 or 1/3 of the screen width (depending on the screen size) and it's easy to keep just the right context visible.
I do wish it had virtual outputs though. Such that we can either combine screens to form a big monitor, or subdivide a screen to make multiple outputs. I have been doing some coding on a 42" OLED tv, and I really want both a side tray and an overhead output. There's stilch which does this; I wonder if River is capable enough to do something similar. https://github.com/wegel/stilch