A friend of mine recently acquired what is known as a mini drop hydraulic neck trailer. I haven't seen the trailer yet, but I know their design is to travel at minimum legal road clearance. I told him that the first chance he has to pass by my place with the trailer I need to install an over-ride solenoid to the suspension leveling valves on both his tractor and the trailer and a switch in the dash. This can add an extra 4inches of ground clearance for emergencies. I can also add a dump solenoid on the trailer which will allow it to drop to 1" ground clearance in case of a questionable overhead height. The pony motor units that operate the necks on trailers can be fitted with remote starting and solenoid valves to raise and lower from the cab, but this requires a lot more expense.