I agree with the others. Do not haul in an enclosed Uhaul!!!
An open top trailer should be ok as long as the calves can be kept out of the wind. The open trailers i am familiar with can be fixed with a large tarp placed over the front of the trailer and covering the front,top & sides 6-8ft back from the front. Use plenty of bungee cords to keep the tarp from flapping in the wind. If allowed to flap the tarp will self destruct.
Bed the trailer with straw or wood shavings. As long as the calves are kept dry and out of the wind they should be fine.
Before your trip consult a local vet for his advice for needed vacinations.
Make the home bound trip in as little time as possible. Plan the return trip to avoid bad weather.
Before leaving on this trip make sure you have a pen with very good fences in place. These little guys will be headed back to Florida if they get out when you get them home.
When they get to SC first feed them some good quality grass (not alfalfa) hay. After 2-3 hrs on hay, feed about 5 lb of high quality calf starter (min 18%protein). Continue to feed all of the hay they will eat, along with all the calf starter they will eat until they have consumed 1-50lb bag of calf starter. When they have eaten 50lb of starter then switch to a grower (approx 14% protein) at 5lb/hd/day plus free choice hay or green pasture. Continue this feeding until breeding size.
High quality nutrition is very important the first 30 days. If they get past the first 30 days with no sickness then you are pretty much home free. Check them first thing every morning, looking for holding head below shoulder level, droopy eyes or ears, lack of appetite, or soft cough. The first few minutes of observation should be from far enough distance that they are not aware you are around. If you approach them immediately, this will cause their adrennalin to kick in and mask their true feeling. Don't be too concerned with a clear nasal discharge if appetite is good and otherwise feeling good. However, yellow or green nasal discharge could indicate an infection is brewing. Check with vet with any concerns.
Good luck and best regards
Brock