|Yes, it does apply.|
I want the computers on network A to see the computers on Network B and viceversa.
If you want communication back and forth between Subnet A and Subnet B, creating a second, separate subnet is a moot point and you should just use a single subnet and completely forget about the 2nd router altogether.
Reread my guide and pay attention to the version (I believe it's version 1) wherein you interconnect the routers "LAN port to LAN port"
IMHO you're overcomplicating this by introducing a second subnet. KISS (Keep It Simple Stupid) is a good rule of thumb to live by in computing and in this case you're not doing it (ie: keeping it simple)
If you feel you absolutely have to have a second, separate subnet, please explain your logic and reasoning. I confess I'm rather curious about that.
Oh and if you have to have a second subnet, my guide still does apply, only you'd use the other version wherein you interconnect "LAN port to WAN port"
I made that guide to help out people like you so if you're having issues understanding it, there's not much more I, or anybody else, will be able to do.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.