I posted this a few days ago on another thread. I have noticed watching live streaming of long trains at BNSF and UP on the trains website at a double tracked diamond , they both use quite frequently power at the head, a helper midway and a pusher at the rear. Thought it'd be cool to try it myself. Found it's a difficult exercise with MTH P-2 , impossible with TMCC motive power without derailing RS and its not in the cards with LC+. However, with Legacy engines and Odyssey on, here's a SD40-2 at the front, a GP-35 midway as a helper and a 8 year old GP30 in reverse as rear pusher pulling a 15 car train. It ran fine at any speed. BTW, I took 12 pieces of RS off the train to shorten the video...
Joe