This. Go for tethered capture on a pair of old dSLRs and use something like an rPi or just bloody long cables to pull the images to an always-on linux box. Have

This. Go for tethered capture on a pair of old dSLRs and use something like an rPi or just bloody long cables to pull the images to an always-on linux box. Have a look at this to get started -- https://entangle-photo.org/ https://entangle-photo.org/ -- which works with many canon/nikon bodies. There are a few "lithium to power" hacks (e.g. "ONsite Relay A Camera Power System") but they are expensive and often many of the bodies can power themselves over USB. A bigger problem you'll have is condensation and generic detritus if you want to leave it outside unattended.