Obviously ballast it about as realistic a trackbed as one can get. For those who don't want to go to the trouble of applying ballast here is an idea. I took cork roadbed and using a spray bottle gave it a quick spritz of water which slightly raised the grain of the cork and then, while wet I gave it a light coat of water based porch enamel. The result gave a sorta gravel like texture to the cork.
I think it could be used as is or ballest could be added to the outer edges without needing to put it between the ties.
Just an idea for us lazy folk.
Jim Lawson