Is there a respectable scholarly position that would ratify/explain an orthodox date for the Pauline Epistles (50-60 CE) and a late date for Luke-Acts (100-125 CE)?
Dale Martin of Yale University (a Professor of Religious Studies - not strictly a theologian) suggests in his undergraduate course that the names for the gospels were attached to them significantly after their writing. Therefore they could not be dated by knowing the author and historical criticism techniques (such as dependency of Luke on other works, seeing Luke as part of Luke-Acts which suggests it is after Paul and Peter are out of the picture etc. etc.) which may suggest a later date could be used.
In this case, we can have early Pauline letters and a late Luke-Acts.
Alternatively, if the historical Luke did write Luke-Acts, he could have been much younger than Paul and therefore have written it at a later date. There are multiple ways this could be logically consistent.
Early date for Paul's undisputed epistles
Paul's epistles were written by Paul. Since his mission covers the time of King Aretus of Nabataea as well as the Great Famine, we can reliably date the epistles to around the first half of the first century.
Possible dates for Acts of the Apostles
The assumption that Acts must have been written within a generation of the life of Paul is based on an underlying assumption that Luke was the author of Acts. However, both the Gospel of Luke and Acts were originally anonymous and were only attributed to Luke later in the second century. Modern arguments for Lucan authorship of Acts include the eyewitness nature and considerable detail that it contains, but this need only suggest good rhetorical skills. Ehrman says in Forged, page 208, that at just about every point where it is possible to check what Acts says about Paul with what Paul says about himself in his authentic letters, there are discrepancies.
John Shelby Spong says, in Born of a Woman, page 109, the author was a Greek-speaking gentile and did not understand Jewish law. That was certainly obvious to the Church Fathers, when they sought to attribute these works to a gentile who knew Paul well. Bart D. Ehrman says (ibid, 207), that the idea that Paul's companion Luke was a gentile comes from Colossians, a book that appears to have been forged in Paul's name after his death (a Luke is also named in Paul's authentic letter of Philemon, but nothing is said there about his being a Gentile). There are three persons in Colossians who were Gentile companions of Paul: Epaphras, Demas, and Luke the physician (Colossians 4:12-14). Ehrman says it seems unlikely that Demas could be the author, since we learn elsewhere that Demas "abandoned" Paul (2 Timothy 4:10). Epaphras appears to have been known as the founder of the church in Colossae (Colossians 1:5-7), a church that is never mentioned in Acts. That would be odd if its founder were the author. Ehrman says this reasoning leaves just one candidate, Luke the Gentile physician.
Spong (ibid) says the author of Luke/Acts would not have been Paul’s travelling companion because of the large number of discrepancies between Acts and Paul’s epistles, pointing in particular to Galations 1:16-17 and Acts 9:19-29, which give very different accounts of Paul’s travels from Damascus. With no evidence to support Luke as the author of Luke/Acts, Bishop Spong believes in early Pauline epistles and late Acts of the Apostles.