Do you have a diagram of where the access points are?
Do you have a picture of any of the access points?
Are you using RF plan to see the coverage of the access points?
You probably know that the AP60 is a single-band access point that probably only operates on the 2.4ghz band. It could be difficult to make a 2.4ghz only band AP work with high density.
Band steering would not be useful, since the AP only offers a single band at a time.