You definitely want any solar panels to be wired through a charge controller.
To operate the jacks you need a battery connected to the control box for the jacks. The solar would charge the battery and would indirectly help with voltage sag as you use the jacks. Ideally you should have enough battery to run the jacks without the solar helping the battery maintain voltage. Sizing the solar should be based on solar array size not any specific load.
Don't use the load terminals on the solar charger. Feed the dc power center from the battery. That's how the camper should have been built. This load terminals on the charger have a very small load value.
The jack controller should have fuses, one for each jack. They are normally blade type fuses and will be marked with their rating. The actual power consumed will be less but it should give you an idea of roughly the power demand in amps. Typically a single healthy battery should be able to raise the camper off the truck.