The "we/us" may actually have included non-Jewish Christians who were with Paul in Rome, so Paul would not be distinguishing between "us" (Jews in Rome) and "you" (Gentiles in Ephesus). The Tychicus, who hand-carried the letter to Ephesus (Eph 6:21), was the same Tychicus, who hand-carried the letter to Colossae (Col 4:7). That is, these two letters were "prison epistles" which Paul wrote from Rome. Tychicus had hand-carried these two letters to Asia Minor at the same time in the same trip.
Having said that, the "we/us" with Paul would therefore have to include believers who were not circumcised, that is, they are enumerated in Col 4:12-14 as Epaphras ("one of your number"), Luke, and Demas. In other words, these three names are mentioned after Paul finishes in Col 4:11 finishing with "Justus... who are from the circumcision." He then mentions the non-circumcision, who (again) were Epaphras ("one of your number" and therefore a Colossian), Luke, and Demas. To put it another way, Epaphras, Luke, and Demas were Gentile believers who must have been physically with Paul in Rome when Paul had written the epistle to the Ephesians, which Tychicus subsequently had hand-delivered to Asia Minor with the Colossian letter at the same time in the same trip.
So the "we/us" in the Ephesian epistle are believers in Rome "who first believed" (Jew & Gentile) and the "you" are those in Ephesus who believed later and who were of course exclusively Gentile believers (according to Eph 2:11-12). So the emphasis falls more in line that Gentile believers are included in a body, which is already comprised of both Jews & Gentiles, and of course Paul foot-stomps this in Eph 2:11-22.