First off, welcome to AirForums!
I'm pretty certain a '74 Sovereign's loaded weight is going to be well over the 5,000lb maximum towing capacity of your Crown Vic, even with weight reducing measures taken.
Check out page four in this Floor Plans Sheet
. Depending on the interior layout - the original weight ranges from 4,970-5,065lbs dry weight. The "dry weight" doesn't include added features like an awning, water or anything you put in the trailer or car.
Could it "move it"? Yeah.
Is it going to be an enjoyable road trip? No.
Generally, when everything is tuned up and running perfectly, you should leave a 5-10% buffer minimum in the "actual towing weight" of your trailer versus the "maximum towing capacity" of your tow vehicle. A Sovereign
is a big trailer. Additional modifications would probably have to be made to your CV.