Intermittent electrical power... Are the computers using battery backup or laptop style with built in batteries?

Are you also providing networked data/file sharing, email server, etc?

Is data integrity a concern between power outages and potentially weak/unreliable WiFi network links?

Regarding stable power for WiFi repeaters and other gear, 12 volt batteries can be a potential work around. Big car or truck batteries can power network gear for a long time. Periodic recharging can be done via connection to a portable generator or even jumper cables to a running truck or car.

Technically the batteries should be 'deep discharge' type for longer useful life, but regular truck/car batteries (aka engine starting batteries) tend to be more commonly available. And those will work well enough as long as they are regularly recharged before being allowed to drain very low.

Just need a simple box to tuck the equipment into and have the big battery sitting nearby. Keep the battery well ventilated and not in the same cabinet as the electronics. Sulfuric acid fumes from the battery can degrade electronics gear.

Power over Ethernet is one way to get electricity to remotely mounted equipment. Downside is that long wire runs limit the maximum available current. 48 volt PoE has less wireline voltage losses than 12 volt PoE. Or just run a dedicated power cable in a parallel trench.

Buried network cable should not be the thinly protected above ground stuff. Burial tends to be hard on the cable so the type intended for burial has a very tough outer jacket to resist crushing and intrusion of sharp edged rocks, etc. Of course the tough direct burial cable type costs more and may be hard to source locally.

You only have one week on the ground there due to other commitments elsewhere?