I am working with this setup myself. Further research has told me that in the SMC device (login: cusadmin/highspeed to http://10.1.10
.1) will require several settings be made on the Firewall screens. Be sure all checkboxes are checked that imply a disabling of routing or translating. There is another sub-screen called something like Absolute Static IP Management that has an appropriate setting that needs looking at.
Sorry, I am not able to access my SMC device right now, so exact instructions will come later.
Making these settings will put the SMC into a (euphemistically called) "pass-through" mode (NOT "bridged" as many hardcore networking techs will vociferously explain). In this mode (so I a led to believe), the public IP (static) address will be seen on the SMC's ethernet jacks. I have yet to come to understand how/where the public IP (static) 'gateway' address is used (for me, the public IP gateway address one number less than the public IP).