The hitch weight for a '68 Sovereign
30' is indeed 415 pounds and the ball height is 19 inches as you were informed; however, there is more than hitch weight to consider. You'll need a vehicle capable of towing the 4640 pound dry weight plus a margin of 500 to 1000#.
You should also have a weight distribution hitch with some sort of sway control device.
Tires are a topic of endless discussion and controversy on these forums. Just make sure you get real trailer tires of the correct size and keep them fully inflated for the trip home. Don't let the boys in Santa Fe convince you that passenger car tires will be fine for one trip.
You mentioned wheel bearings. Make sure they are packed by someone who can inspect the bearings and the spindles as well as the electric trailer brakes.
Hope this helps.