The 90 feet limit for advanced open water divers is a maximum safe depth. I don't think it's a compulsory depth
The "experience a deep dive to 90ft" AOWD-thing is for people with no pressure related limitations. For you 60 feet is probably "deep" because of the imminent danger that you pump takes some damage, and you need to limit your time down there. Hence, I'd say that your dive to 60ft would be reminiscent of a decompression dive and is equal to or more serious than the 90ft dive for people without a pump.
Just find an instructor that is willing to certify you as an AOWD diver or equivalent without actually going to 90 feet. Maybe 60ft?
You could then proceed to rescue diving cert, which would teach you self-rescue, risk management and other cool things.