You might consider a trailer with a wheel lift behind it. Think the little single axle car haulers that they rent at U-Haul. Put the Crown Vic on the trailer, hook the car hauler to the back end of the trailer and put the half ton drive wheels on it.
Shorter than two trailers, and cheaper.
In fact, if you put a receiver type hitch on the back of the trailer, you could just rent the car hauler if you needed it.
But, you really really need brakes on the trailer.
With that much weight, I would put them on both axles.
They also sell actuators that will mount in the half ton and apply the foot brake upon commands from the tow vehicle without modifications to it's braking system.