This is not correct:
route xx.xxx.xx.128/25 next-hop xx.xx.xxx.30; ------> /25 Network (Additional public IP)
Your ISP will route xx.xx.xx.128/25 to YOUR side of the /30 network.
You will use them downstream on your SRX from there.
You can just configure static or destination nat directly (no proxy arp needed as noted above)
Or you can break them into subnets to route in your internal network.
Or you can put an interface in that subnet or smaller ones directly on your SRX.
But you cannot route them back to the ISP this is a routing loop.
