Correct, proxy-arp means you do not need the address on the interface and in your example you can't put the address on the interface because you are sending all ports.
This is the more typical examples starting on page 8 of this document. You specify both the ip address and ports you want to forward and then this allows you to use the same address for multiple devices.
This specification then also allows you to use the same ip address as the interface. But if you use ports that the SRX also uses like SSH or http you would need to reassign those services to non-standard ports on the SRX first before using the port forwarding for a server.
https://kb.juniper.net/library/CUSTOMERSERVICE/technotes/Junos_NAT_Examples.pdf