not sure how long ago you served, but for me I only discharged 3 years ago.
1CHB had 2 mobile ICU capabilities, that they were looking at increasing. Granted these are usually used in humanitarian deployments, but there is doctrine in Med PAMS that have contingencies for local use.
on point 1, you have to also consider the ability some hospitals have around australia to transition trauma wards into Intensive care units when required.