DWRAT DW, If you are going to tow a trailer with a dually You need low rear and front mud flaps on the truck. The closer to the gound the better. With full load I am 4" off ground. You would believe the stone clips, garbage, junk and died bodies you pickup on the interstates. I trailer my cobra for 12 years to the R&G from NJ to St Lious. It takes 1 hour to wrapup the car. I found that sheets of scuba foam works the best to protect the car and paint. Over this a added moving blankets and finished with a water proof tarp. about 20 bungie cords to keep everything tight on the car at 65-70 mph. Over time this got to be a pain. If the track has garages you have a place to stay out of bad weather, if not, your wet. I finally went with a Haulmark custom. Plain Jane special. 10,000 pound trailer. Cabinets in the front with working top. Both lights for 110 and 12 volt. Drop 4" axles. Brakes on all wheels. Some trailers have 4 wheels and only 2 have brakes. I went electrical instead of surge. Trailer height is 6" inside. 24' length. It has a 6" slope nose but is not a Vee nose. I will add a "Pace" bubble front to help with the wind buffeting. This is the best money I spent. Down the road, I may add AC. I have a 8000watt generator that fits under the front cabinet. Thanks to Sandy. Trailer was wired for this or external hookup from out side. The MPG lost between the 2 is 1.4 miles per gallon at 65 mph. Still getting over 10 mph with SBC dually running up and down mountains. With open trailer at 65 was getting 12.8-13.2 I looked at the lowhauler from Haulmark that the motorcycle guys use. They dropped their 20' one and the little 16' gives you no room to move around and also there is no clearance for the car inside from right to left. you have about 3". IF you go full size trailer, go the 24' one. It pulls well, stable as hell at 70 mph. Get a full metal floor and extended dove tail rear door. You will need to jackup the trailer to get a low car out of the trailer without bottoming out. I did this on mine.
Couple of side notes, Have the trailer frame undercoated. Extends the life.
You don't need an equalizer hitch with a dually but recommend one or at least an anti sway bar setup for cross winds from trucks and weather.
Mudflaps. I have aluminum ones that drop down to 10" off the ground. I picked up trucker mud flaps on the highway and cut them to clear the road by 4" They are plastic. This stops 98% of tire pickup off the road from hitting trailer. My trailer has the rap around the front with diamond plate. It did get some hits even with my setup. Rivet the pastic with 3-4. If hit hard will break off with damage to rest of mud flaps. Trailer places also sell wisker kits that mount to the bottom of the rear bumper that help deflect road debrie.
Make sure the trailer is level when hooked to the truck and with full load you would carry. I run a 4" drop on my setup. If you have to get an adjustable tow hitch for the ball height, get the nut welded or drilled and pined to pervent possible trailer seperation. I had this happen with a hitch and trailr I had towed for years. Vibration loosened the nut. It had a locking washer on also. DON'T trust it. You only need a small spot weld, or drill and pin with a tension pin. If you need to change the balls, grind off the weld or drill out the pin.
Last note, Maintainance, Check all lights, Grease all wheel bearings, same for hitchball and cup of trailer hitch. If you travel at night like me, Reflection tape on the back and sides of the trailer. Have had the open trailer hit 4 times when driving. You should see the amount of damage a steel fender does to an aluminum and plastic car body. Just pull out the fender on the trailer to not rub on the tires. Also check tire pressures. They will go up from 6-15 pounds with driving. This depends on how hot it is out. I Nitro fill mine at work and the max is about 3-4 degree temp with full load and highway speed.
Sorry for long story, last note. If you see a mess on the road road that looks like some one spilled paint there, slow down and look for ROADKILL. It's big here on the east coast.
The dogs where under both trailers for a week and the smell was bad. Multi power washes needed. Good luck Rick L.