I thought that Netflix only allowed you download to mobile/tablet devices, but apparently you can download via the Windows 10 app:
https://help.netflix.com/en/node/54816
I haven't tried this myself, so I'm not sure on the limitations. Because the content will be all tied up in DRM, I doubt you could download to say a USB drive (from some Windows 10 app), then plug it into a Windows 10 PC running in his trailer.
Most likely you would need to take the physical PC, connect it to the Internet and go on a Netflix download spree, then bring that PC into his trailer. A bit of a hassle.
I would take a look and see if you can get the HDMI from the tablet back working. Maybe via downgrading the OS (assuming the tablet is not used for anything critical).