My Kubota M6040 has RimGuard in the rear tires, grapple on the FEL and HD rear blade. It weighs 10,000+ pounds. My soil gets hard enough, this time of year, the tires only leave "trace marks" in the dirt.
I only have a single shank ripper. Under these conditions I can pull this ripper to a depth of eight inches with no problems. Want it deeper - hit it a second time. I'm certain I could pull a three shank also. Most likely to a shallower depth on the first pass.
My suggestion. Get the 3 shank ripper. If it doesn't pull deep enough - remove one shank. OR - start shallow on the first pass - go deeper on subsequent passes.
My BIG problem with use of a ripper - ROCKS. I just get going and a big 'ol rock causes the spring trip ripper to trip. I've gone to using a disk harrow. At least it will ride over the big rocks.