Bake cake mix in a 9x13-inch pan at 350°F for 25–30 minutes; cool 30 minutes.
Cut cake lengthwise into two slabs; stack with a thin layer of chocolate frosting between.
Crumb-coat whole cake with chocolate frosting; chill 15 minutes.
Spread orange frosting smooth; leave one short end lower to mimic a dump bed.
Press crushed cookies around base and on one side for dirt.
Break graham cracker into a road; place alongside cake and add sprinkles as rocks.
Set the clean toy truck on top, with a bit of frosting under wheels to secure.