My truck has a leveling system built by Equalizer Systems ( Equalizer Systems | A Days Company | Official Site
). My previous and first rv was an Allegro class A with HWH levelers on it. They were the kind that hinged down on a pivot and then extended. I had some problems with it. HWH used proprietary stuff that makes it impossible for any old hydraulic repair place to work on. I had to send a couple of my units in for refurbish. They did a good job fixing them I think, and the cost wasn't too bad. But I'd rather deal with a local place. My Equalizer system has only had one problem. They have a small switch that tells the controller when the jack is fully retracted up. Two of those switches failed on me. They told me they figured out those vintage switches weren't very good and have an updated switch. I replaced the two (price wasn't too bad for the switches and they look a bit different so there must be something better about them) and haven't had any problems. I would for sure contact them about a system for your truck.
'03 Freightliner FL112, 295" wheel base, with '03 United Specialties 26' living quarters, single screw, Cat C12 430 h/p 1650 torque, Eaton 10speed , 3.42 rear axle ratio