I would go at least 4K... just wait until you bend a tie rod so you are toe-in or have ac aliper seize or have flat tires and have to pull the rig up the ramps with the wheels locked....
A 2K would be fine if the rig had 30psi in the tires and rolled freely, but then you wouldn't need the winch....
EDIT- a problem with the 2K winch is that the spool is only long enough for 50' of wire that is only rated at 2K lbs. Put a snatch block on it and your wire is only good for 4K (kind of) and is only 25' long
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