I got it to work with a little trick, using nonstandard subnet masks:

The primary router's internal LAN is set to:

 - Router IP: 192.168.1.252
 - Mask: 255.255.255.0

The secondary router is connected through its WAN port to the primary.  
Its internal LAN configuration is set to:

 - Router IP(secondary router): 192.168.1.1
 - Mask: 255.255.255.128

Its WAN Configuration is set to:

 - Gateway: 192.168.1.252 (The primary router)
 - Mask: 255.255.255.240