Leveling can be a matter of "How much money are you willing to throw at it to make it easy?" From scrap bits of lumber and a cheap level all the way up to really expensive electronical hydraulic self leveling outriggers (such as large cranes have) and everything in between.
Ask yourself (and your partner) this: How much level do you need? I doubt anyone on this forum really *NEEDS* anything perfectly level to within a few microns. Most of us aren't setting up billiard tables either. For plumbing drainage and basic day-to-day living, within an inch or so, side-to-side and within a couple inches, front-to-back, will be "good enough" for most folks. As a long haul driver, I parked in many sloped lots for an overnight sleep and despite the slope, slept just fine (after a little getting accustomed to it).
Some folks want jacks instead of boards/ramps under the tires because it will greatly reduce movement from the springs and suspension as you walk around inside.