When playing with Modest Maps Ginger Island Farm, the island farm minecart placement ends up out of alignment with the surrounding terrain. See the screenshot.

Ginger Island farm replacement maps are not nearly as popular as main farm replacement maps, but there are a handful of them on Nexus. It might be worthwhile to make the cart placement configurable (as you've done with the regular farm maps), even if you don't add explicit support for this specific island farm.