This is the current layout of the network, except that the routers feed into separate switches: the Zyxel pictured and a smaller trendnet 4-port switch. I presume I could segregate the networks with the Zyxel GS1510, which is a managed switch. But that is above my pay grade. BTW I'm using the ASUS routers in wired mode only.
Also, I am not looking for load balancing or fail over. I'm simply looking to restrict some of the devices on my network to one isp and other devices to the second ISP, yet still retain the ability to monitor or access each network client from one PC.