As a concrete contractor I recommend pouring thicker under the bases of where the lift will be positioned. Little pier footings with a simple rebar grid. If your slab is 4" then just dig another 8"x16"x16" where the feet of the lift will be. 1/2" rebar is plenty strong if it's 60grade. 3000-4000psi is plenty. A house foundation only calls for 3/8" rebar @18" on center and 4" thick 2500psi. I also only use big rock concrete (3/4" pump mix). The minimum I pour is 3000psi. Pea gravel is not structural concrete. It was only intended to grout block walls. It's fine for a walkway or patio. But if you are parking on it, I would pour big rock. Also be sure to let the concrete cure for at least two weeks in this weather.

I can explain it to you, I can't understand it for you.