At the moment I am definitely fit enough to walk 20 km a day for an extended period of time, and have done in the past. But the thing I am not so sure about is preparation: gear, food and training up for the task.
Do not overestimate your hiking speed on day hikes. Doing them back to back hikes can slow you down alot, and the landscape maybe harder. So i think they say a good rule of thumb is 65% of your day hiking speed should be your planned average speed while on a distance hike.
If you have no time frame that you MUST complete the trip, then no worries, but if you have to get back to work or something, you might want to tack on another 2 weeks of vacation time.
1. Gear recommendations - currently I own some shoes, a backpack (though it's unlikely to be big enough), the requisite clothes, and that's it. So any recommendations for for tent, sleeping mat, etc.
Figure out how much weight you want to carry, then start adding up your gear. Before you buy anything try and plan it all out. There are a few good free sites that help with that stuff.
https://lighterpack.com/Depending on how cold/hot it gets a thermo pad will save your butt. So i would get one, 3 basic types to pick. You can easily good thermo pads and find info on the 3 main types and figure out which one is best for you.
As for a test, i love the Big Agnes Bitter Springs UL 2 Tent (the two person is very roomy for 1 person!)
Backpack, i actually use an old heavy one, NOT meant for long trips but i too cheap to buy a better one.
2. Safety recommendations - what are some reasonable ways to be proactive around safety. There will be snakes, but they are unlikely to be as big a problem as, say, dehydration, potentially twisting an ankle, etc. Are there safety trackers, GPS, or other gadgets that are likely to make a big difference
EYES! Your eyes and ears will help the most for the critters.
Being in aussie i guessing a firearm is a no go? For me an extremely light firearm, under 1kg, is normally brought along. But if not, then a decent knife and peperspray (also helps with the bears in the states)
For dehydration, i have only done long distance hikes where water is "normally" found at least every 50km (generally close to 20km) so just carry enough water for 2 days to be safe. I am a HUGE fan of Sayer's filters! So if you have sources of nasty dirty water, that is water!
GPS i use an etrex 20, battery life is about a day if left on, and can store TONS of tracks, has decent screen, and is very tough.
There are the satiliate GPS systems that can do SMS, even phone calls, and they all do the 911 thing where they can send out a signal. Those generally have a high price and monthly fee.
And i carry a very very basic first aid kit, stuff to safe my life, not to make me feel better :D
3. Food recommendations - the trail is 'self-sufficient', so water and food are things I have to carry. There will be drop offs, though how frequent these are I am not sure of yet - reading a few blogs about the trail people drive one way dropping off their food along the way, and hike back picking it up.
Due to the nature of Australia most of the trail is fuel stove only - no fires. It's also possible that there might be some days where stoves are banned due to extreme bush fire danger. What sort of food is viable? Dehydrated? Dry? Something else?
I became a HUGE fan of dehydrated food, super easy to cook at home, and they compact like crazy! There are also pre-made dehydrated food you can buy online, but the "meals" are 7-15$ (USD) each, very high price. I also generally only do long hikes where there is a store or a public road at least every 50km. So i can easily hitchhike into a town and get more food.
Instant potatoes, and oatmeal are also very good, high cals, lightweight and just need to add water.
4. Other tips, advice or ideas based on what you guys have done - anything to make the training, or the hike, easier, more doable, etc?
Work out smaller trips then work your way up! Planning is key, and having a good path of where to get your water supplies and food at.
I didn't really look at your trial, but having "pickup" points where a friend can mail you your food packets is also pretty cool!
Do not worry about smelling good, or how you look. You will smell! Just stay clean on the medical side of things. Keep teeth cleaned, do not let stuff grow, etc...
And final thing, here is my little list of possible gear while i was buying up for my future OREGON section hike of the PCT later this year.
https://docs.google.com/spreadsheets/d/1vOLj0uYKxB9wFqsKFK9aRRmP07Bt7jCGLt_tp_xEWHw/edit?usp=sharingedit:
After reading some other comments.....
Poles are super nice once you get used to using them, they take the load off your feet by like up to 30% (think that is what i read) and you will be able to go alot more before getting sore.
Another one to save on weight, poles can be used instead of normal tent poles! Super handy :D You can see that in my gear list ideas in the link above
Also having a good real map is needed, and know how to use it properly. A GPS device can fail.... get lost or destroyed.
Solar panel chargers are NOT pratical if you are in a hurry, or in any type of shaded area.
edit2:
Following someone's video blog of a long distanct hike helped me know what types of things to think about. One of the ones i watched a while back was this lady.
https://www.youtube.com/watch?v=TSWTjQ0p3nU&list=PLXiz2lWve6AK4uaerP03vXav_HMs1YG6XThis is the AT in USA.
And currently she is in the middle of hiking the PCT, so the playlist is not completed yet, i think last video she actually had to get off the trail for some reason (i am a few videos behind)
https://www.youtube.com/watch?v=N9cv1hsggzA&list=PLXiz2lWve6ALxbJ3nURBtwQAnrbi9lLHN