Have you looked at Campy Ekar? They have a 10-44, 9-42, and 9-36 13 speed cassette. Paired with 38, 40 and 42 tooth chainrings gives you lots of options.
I run the 40t chainring and have all three cassettes. 9-36 for most road, 9-42 for mountain rides and easier gravel, 10-42 for tougher gravel.
Works really well for me