NSW Drink Driving & Traffic Offences

My son is about to come off a 9 month DUI suspension and we have just been told he will require a interlock device. He is a 18 and a first year apprentice. He is required to travel to different sites depending on where the job is. When he was charged with DUI his job was in serious jeopardy so my husband and I gave a guarantee to his employers we would make sure he got to site on time. This would mean driving him at 4.30am in the morning and then going to work ourselves after which we would have to travel sometime an hour after work to collect him. He does not have a car and will not be able to afford one for quite some time. We were hoping he could relieve us from some 4.30am trips and have a loan car occasionally, especially to far away sites. He will also be required to drive his employers work van. Can I get some advice on applying for an exemption from installing an interlock device? I have heard it is extremely difficult to get. My husband and I are exhausted working full time and driving our son to work and really do not feel we could not physically or mentally continue living this way for the next 2 years. I would appreciate your comments.