I use Chrome Remote Desktop. Its easy to setup in windows, a bit trickier in Linux. You install it and then you can access your machine via google chrome from anywhere. It’s a client-server based system, so there are no open ports inviting hackers to come and have a go. How secure is it? As much as the next virtual desktop system. Do I have to trust google? Yes.
Change external IP addresses from time to time, by turning off your router for 10 minutes once a week. Might help, probably not all that much.
I have been away from my server rack for 2 weeks and have plotted about three hundred plots and earned some Chia through pooling. The machines are Dell servers so I can access them via iDrac a remote control system which operates outside of the operating system, this allows virtual console (like remote dekstop from one machine to another) and so they can be remote rebooted and/or power cycled etc… if required. These machines and this functionality cost me less (they were second hand) than a decent new PC would have cost and I have enjoyed delving into some server stuff which I have recently learned. I have installed a camera to watch the rack physically, and wifi plugs so I can monitor power consumption and kill the entire thing any time I want. I have a redundant internet connection provided by a 4G router in case the primary connection (at my workplace) goes down.
As an example of how I admin this system remotely. I have been changing the final drive destination as drives fill up, every day for a few weeks. I have one machine today that I cannot currently access via chrome remote, but I can iDrac to it and when its current plotting jobs are finished I will remote reboot it.
You have had good advice on keys and mnemonics etc. Keep your key printed out somewhere safe, and from time to time shut down chia and back up your DB files. Are you backing up your /db folder? - #7 by Harris. If you had to reinstall your machine, you would just reinstall the op-system, then any security software, then chia blockchain, copy the backup of your DB files (not critical but it saves you days of syncing), enter your mnemonic and you are back. If your plots have survived, which they should have done unless it was a lightning strike that took out your equipment, point your chia GUI at them and hey presto.