I carry along five (5) three-step blocks along that I made out of 2 X 6's, plus extra pieces of 2 X 6's. The plastic three-step blocks break too easily when camping in off-pavement rocky campsites.
Also for Boy Scout readiness, you need to carry along the capability for leveling in a worst case situation: This would be a 3-point leveling ... where you are on a slope that is tipped slightly both from side-to-side and front-to-back. In that situation you might have to raise both rear dual tire sets (requiring 4 three-step blocks), along with one front tire (requiring 1 three-step block). Our camping style is to be ready for any situation, and we have needed to do 3-point leveling several times ... not for refrigerator reasons ... but for walking around and sleeping comfort inside the coach.