@Scott B
I see your post for a 2005 31 but as pessimistic as I am, it did not say 310 nor the specific year but will rely on that. That is more like it on the height. I pulled the first 306 wing keel with my tandem axle back from the plant to my dealership with the mast on secured on top and went under all bridging without any issues and clearance leaving over a foot of clearance on the trailer. I did measure the ends of the mast and was very careful going under bridging but more so at gas facilities. Thank you sir. It is appx. 10 feet from the highest point to the bottom of the wing keel measuring from the winches downward with the arch down. I use to pull all boats behind my dooley with my trailers one of which which I liked the most with torsion bar axles.
The only mishap was sending an idiot down for a Catalina 310 who allowed the factory to tie down never checking the tie downs nor following procedures to tie down the boat the way I wanted it to the trailer. Boat moved forward enroute nearly collapsing my trailer as the forward straps had come loose at 85 to 90 mph. Burned up an automatic transmission and repaired the trailer which was costly. Of course I fired him.
As for the documents on line from Marlow Hunter, anyway to get them over on line at Sailboat Owners.com?????
Dave alias crazy dave