Gain or lose is a matter of perspective Spanner. As an example, currently in QLD it is 12:35pm, Northern Territory 12:05pm, South Australia 12:05pm if that helps.
Personally, if I'm riding 'on the clock' and crossing timezones I do all of my planning and then just use the bike clock - NEVER a GPS. If your plan is for a 36 hour ride starting at say 04:00am in QLD, you have until 16:00pm QLD time the following day to finish. A clock on the wall in NT would read 15:30pm at that instant.
Regardless of timezones, you only have 24 hours to complete your planned SS1600K ride to Renmark. If you arrive in Renmark (SA), having started in Alice Springs (NT), you won't cross any time zones.