This takes care of it, as long as I start apache2 and postgres afterwards:

hostname -F /etc/hostname

..immediately after defining the hostname.

That gets me to airtime-check-system, the final piece of the build. It fails with this now:

*** Verifying your system environment, running airtime-check-system ***
AIRTIME_STATUS_URL             = http://localhost/api/status/format/json/api_key/%%api_key%%
AIRTIME_SERVER_RESPONDING      = OK
KERNEL_VERSION                 = 2.6.32-5-686
MACHINE_ARCHITECTURE           = i686
TOTAL_MEMORY_MBYTES            = 1034472
TOTAL_SWAP_MBYTES              = UNKNOWN
AIRTIME_VERSION                = 2.0.3
OS                             = Ubuntu 10.04.1 LTS i686
CPU                            = Intel(R) Core(TM) i7 CPU         920  @ 2.67GHz
WEB_SERVER                     = Apache/2.2.14 (Ubuntu)
PLAYOUT_ENGINE_PROCESS_ID      = 5025
PLAYOUT_ENGINE_RUNNING_SECONDS = 12
PLAYOUT_ENGINE_MEM_PERC        = 0.9%
PLAYOUT_ENGINE_CPU_PERC        = 0.0%
LIQUIDSOAP_PROCESS_ID          = 5027
LIQUIDSOAP_RUNNING_SECONDS     = 12
LIQUIDSOAP_MEM_PERC            = 1.8%
LIQUIDSOAP_CPU_PERC            = 9.8%
MEDIA_MONITOR_PROCESS_ID       = FAILED
MEDIA_MONITOR_RUNNING_SECONDS  = -1
MEDIA_MONITOR_MEM_PERC         = 0%
MEDIA_MONITOR_CPU_PERC         = 0%
RABBITMQ_PROCESS_ID            = 4595
RABBITMQ_RUNNING_SECONDS       = 11
RABBITMQ_MEM_PERC              = 1.1%
RABBITMQ_CPU_PERC              = 0.0%

I assume this is monit not starting: "+ /etc/init.d/monit start
Starting daemon monitor: monit won't be started/stopped unless it it's configured please configure monit and then edit /etc/default/monit and set the "startup" variable to 1 in order to allow
    monit to start"

So, an overlay.