Let me chirp in on this one as I was known to pick up my 310 and transport them back myself as a dealer on my trailer behind my pick up truck (dooley)
The arch needs to be removed. IF 5200 was used, yes it can be separated but anticapte some gelcoat and glass coming off but that can be fixed. The arch can be turned over and around to travel in the cockpit but the height will need to be checked for sure. Legal height is 13' 6" and you will need to cushion that arch very well suggest carpet and tons of it. Otherwise it will go below the boat if a professional does haul it. Again carpet well and do not let anyone otherwise tell you so. Remove antennas, radar, wind vane (whirly bird) and so on before transit.
If the rigging is left on the mast, make sure the spreaders are taken off and again secure the rigging well. In some places the rigging was carpeted but if you will take duck tape and start with a little of the sticky on the mast and then turn it around so the stick is outside, you can secure fast going around the sticky portion vs. using a lot of line.
Make sure all loose gear is stored inside and secured. Take photos of the boat and note any damage before transit. If there is any additional damage, then you have your record before the boat leaves but suggest inspection immediately on the other end.
Have them provide you with a copy of their liability insurance unless this is one of the recognizable professionals as you say but again verify insurance.
Hope this helps you. I did launch one of these via crane into the water with mast up but I do not suggest that to anyone but did launch and retrieve them with my pick up truck using a standard heavy duty trailer designed by me for over the road. Like I said, I knew that boat all too well.
One other thing, do not use 5200 back on that arch.
