[tor-relays] can dirport be disabled on fallback directory?

[starlight.2017q4 at binnacle.cx]

Lately seeing escalating abuse traffic on the relay dirport, now up to 20k rotating source IP addresses per week.

The simple solution is to disable dirport, but the relay is a fallback directory and I don't want to make a change that will negatively affect the relay's ability to function as such.  Would disabling dirport be a problem?

also:

can a non-advertised dirport be left configured for local-system use while the public advertised dirport is disabled?

does a command utility or method exist for querying dirport documents via tunnelled-dir-server?  including miscellanous documents such as

/tor/status-vote/current/consensus.z
/tor/keys/all.z
/tor/server/all.z
/tor/extra/all.z

/tor/server/fp/<fp1>+<fp2>+<fp3>.z
/tor/extra/fp/<fp1>+<fp2>+<fp3>.z
/tor/micro/d/<hash1>-<hash2>.z
/tor/keys/fp/<v3ident1>+<v3ident2>.z

thanks!