Sorry to say it , but with a 31" inside leg, you have no issues with factory low models, all your problem is in just comfort and ergonomics
if i had a 31" inside leg, i wouldn't be on a factory low model
I'm a 30" with a standard height bike/seat. Due to dodgy knees I ride with the seat in the high position meaning I can't get both feet flat, but I happy with that as I don't need to. I do however take care that I don't pull up next to a furrow in the road.