Access to and from this farm, however, does not appear to be entirely limited to that crossing at grade where the collision occurred.
You're correct, there appears to be a good-quality gravel farm lane that goes south from the farm to Newcomer Road. Of course, this results in a rather circuitous route for the farmer to get to/from Mount Joy, as well as other major highways. The grade crossing exists for the farmer's convenience but does not appear to be necessary to actually access the property.
If DA's information about liability is correct, I suspect we may see that grade crossing closed. OTOH, the fact that so few people were injured (ultimately that's a GOOD thing, of course) may mean that this isn't the game-changing incident it could have been. Unfortunately, it may take a true tragedy for this crossing to be closed.