The trick would be to find plants that help filter the water, don't create mess and can survive in a 650 litre tank. I've always found plants useful and the fish benefit from the roughage (grr) but my neighbor is perfectly happy not having plants to worry about.
I've looked at this just in case I had to go fly-in, fly-out and was away for a week or two at a time. People do automate tanks here for FIFO so it is possible.
My high-tech planted tank which requires daily ferts dosing would go. Probably wouldn't miss trimming plants every second week.
I'd look at fancy goldfish, others here probably do natives or cichlids. I'm familiar with goldfish, they are hardy and I could skip some tank heating (this was looking at reducing costs). Stocking would be halved. That's critical - higher the stocking, the higher the waste. I'd keep multiple filters (already have), just in case one fails (this is assuming I'm away 2 weeks at a time).
Ornaments would be very simple and round edges. A goldfish with a scrape and bit of fungal infection might be ok until you get back. $100 discus I'd be stressing out on if ok or not.
That's also why I would do large, hardy and cheap fish as if something goes wrong you are not there. Depends how long you are away, as I said people do nice 6ft automated tanks here that cover if power fails or heaters stop working.
Water changes would need to be weekly or bi-weekly and I'd do 30 to 50%. That's open for debate. Something like a python or water changer will help.
https://www.amazon.com/25-Foot-Python-Aquarium-Maintenance/dp/B000255NXC
Automated fish feeders would be my preference and the darn things require testing imo, not just set and forget. I find changing food levels in the container can change how much fish get. Food blocks I find either dissolve too quick or too slow or the fish sit there having a pig-out.
I have timers on lights and everything so eg lights come on, filters stop, automated feeder drops, etc. One to check is what happens in a power failure, especially with sump setups and restarts.
Plants I would either do Java Fern tied to driftwood (closer to light) or vallisneria (mine is a deep tank but once one shoot gets near light, runners should slowly spread out). Or just skip plants and increase water changes. Personally I find a spend more time on plants then anything else. (Unfortunately so do the fish sometimes).
Simplicity would be key for me. Aquaria I find is both a hobby and keeping pets. There's a bit involved but if you have anyone that can look in on the fish that would help.
Last thought is there are people who do tank maintenance eg water changes.
