If you're unwilling to do some cutting and add support, you're looking at Option 1. The problem with this approach is access to the center.
However, if you're willing to do some cutting, etc., then IMHO you're looking at this wrong. With 3 sheets of 48x96 plywood, you actually have 8 panels that are 30x48 and 2 that are 30x24. With these you can make a configuration close to the one I posted earlier, Option 2. With this you have full access and can add sidings, even a passing siding so you can run a 3rd train.