Isn't this be made more complicated than it needs to be? Can't you just connect the second router to the RG was a network cable? As long as both of them have different addresses and use different channels it seems like both of them could use their own DHCP and everything would be fine! Normally the RG will use 192.168.1.254, you could tell you something like 192.168.2.1 for the second access point so there would be any conflicts. Both of them could that have their own pool of users.