I just received my allocation yesterday so I am brand new to ampr. I can't seem to connect to the wiki to see if there's a description of the DNS architecture so some of this may be obvious to everyone else.
Some of the internet providers I have worked with in the past deal with this issue at the time of initial allocation. One idea to insure regulatory compliance would be to automatically generate the A and PTR records for all addresses allocated. The automatically generated A record name could include the callsign perhaps with a text representation of the IP address, just as Rob described. For usability purposes, CNAME records can be maintained so that the operator can utilize whatever name they prefer for their applications. You could theoretically store the CNAMEs in subdomains to help ease administration burden.
Bill