On a trip of any significant distance (over 30 miles), I'll take the rudders off to lessen wear on the pins. However, it's not really necessary and unless you have the 20-style tiller connectors, can be a real pain. In that case, you literally take the rudders off and leave the lower castings on the boat. Otherwise, tie the tillers to the rear pylons to keep the rudders from swinging and / or falling down. For added insurance, tie a bungee around the upper/lower castings to hold the rudder in the up position.
I use a four-point cam-over type tie down system that attaches to the trailer at one end and has plates that that go on the pylon bolts - it clips into those. That way, nothing touches the fiberglass. That system is at the top of page 31 in the Hobie Parts catalog.
For short trips, I'll coil the wires and tie them to the hiking straps. Long trips, the wires come off.
Chafe is the biggest problem when trailering at high speeds. Nothing should be flapping or bouncing around.
I regularly trailer at 75+ mph. I've even had it over 100 mph a few times

. Gas mileage really suffers at higher speeds. Gas consumption goes up roughly as the square of the velocity, so at 80 mph, you're using 4 times as much gas as you are at 40 mph. At some point, the time you gain by going faster is wasted in gas stops.