I couldn't make out whether the intention is to make the characters same-sex or just the actors.
I can sort of imagine a story about a lesbian cowgirl trying to woo a farm girl, but a BROKEBACK-style cowboy pursuing an air headed, stuck-up mama's boy seems ludicrous.
Ted Chapin is certainly opening the door to interpretation, which I think is a great thing. I didn't see Molly Smith's production of OKLAHOMA! at Arena Stage, but I am wondering how similar it will be in the hands (and throats) of opera singers at Glimmerglass this summer? It feels like a big stretch.