The problem is you will be spinning the parts in your transmission (even if it's in neutral) but the transmission's oil pump is driven from the engine, if it's not running the trans has no oil circulation.
You'll fry the transmission.
A couple times in my life I was in situations where I needed to tow something with the drive wheels on the ground, so I simply started the engine and towed it with it idling.
You need a trailer or a dolly, to get the car's drive wheels OFF the ground. Or you need to buy a tow-car with a manual transmission.
