You can't run the bogies in opposite directions - there is only one motor in the model, and it uses a worm drive to the bogies. So, they all must run in the same direction.One of my Locos is a Farish Deltic with all axle drive and all axle pick up, and as such it runs far better than any of my other locos........ Would it be possible to have one bogie motoring one way and the other bogie (at the other side of the isolater) in the opposite direction ? ! ?
It would be interesting to know how the wiring of each loco would cope with some of the wheels having 12V one way and some of the others 12V of the opposite polarity.
The loco will cause a short-circuit in the situation you describe. (There are ways to damage the loco if using two independent power sources, as the loco might, sometimes, experience the combined voltage (nominal 24 volts, in practise probably well over 30 volts) . But this needs two power supplies and a certain amount of stupidity in the wiring of the layout.
You could "protect" things on the loop, with DC running against mistakes. Depends what level of doing things you're willing to undertake. Could be switches (which also throw turnouts), which also isolate sections of track (so they're dead if switch not correctly thrown). Or there are more advanced methods.