How to control additional tethering settings on android phones?
Instead of changing the IP of the phone's network, you might simply change your router's config so usb0 is not in the brige any more but is configured more like a "WAN" port, complete with the usual NAT.  In this configuration, the phone's DHCP server will only serve an address to your router (to use for the usb0 interface), and all the router's clients will get their IP from your router instead.

The advantage also is that if/when you want to get your internet access from elsewhere (e.g. DSL/cable/younameit), you'll only need to change this part, but all the local network config will stay the same.