I don't know about Brooklyn rails, but i got a kid you could call who skates rails all over BK. if you want to cruise up to Harlem, take the 1 or the 9 train get off 125th, around the Columbia University campus, there are long stair sets with slight curves and multiple kinks everywhere. There is one on riverside with rails on the left, on the right, and a middle section with two rails about 1 foot apart, running on each side of a concrete divider that separates the walk up, and walk down sides of the staircase. I think it would be really easy to do rail to rail tranfers on this set. I can't remenber exactly how many kinks it has though. This set runs down from Riverside by Grant's Tomb which is technically 126th or 127th and riverside. The steps run all the way down to the start of Tieman st. Not that sketchy either because only Columbia kids are on it and its surrounded by trees.
This would actually be a great spot to film. Grant's Tomb and the Hudson River in the background.