Yeah its possible, this is what it looks like with a 136" track in the middle, I would verify the load capacity of your trailer, 3 sleds full of gas is pushing 1900 lbs (1600 for 3 skidoos) the sled in the middle rides on top of the spare to raise the back end allowing more room to push the middle sled back further and to keep it off the other two sleds side pannels.
...and the Elcamino tows that ok?