I don't have history in Juice, but I do have a background in broth production. We also processed in large tanks, with agitators inside. We used an automated CIP system, no confined space cleaning was required. We used a 7-step CIP.
CIPs produced a chart printout, where flowrates of chemicals could be observed. Conductivity was measured in (mS) as a way of determining the concentration of cleaning chemicals used. Operators would also draw a sample for titration during the cleaning cycle to verify chemical concentration. After the CIP, the tank would be inspected by QA for cleanliness. We'd do an ATP swab, as well as a pH strip inside the tank just to ensure the moisture inside was left from the final rinse and not leftover cleaning chemical. From my experience, this process was effective enough to clean a tank after pressure cooking thousands of pounds of chicken parts.
The process was validated before my time though, so I don't have much input for that...but you certainly would want to validate its effectiveness. This may entail some more rigorous ATP swabbing, microbial swabbing, or allergen swabbing. And of course, CIPs don't cover the outside of the equipment, so that portion of cleaning has to be manual!