I recently bought two RBSXTsqG-5acD-US devices, and I would like them to be configured STRICTLY as a bridge, to carry my network across a large field. I do not want them to be set up as an AP, or broadcast an SSID (or even HAVE an SSID). I would simply like it to behave like a really, really long ethernet cable. I do not want any layer 3 setup at all, and also would like (if possible) to disable any web interfaces.

I have used the WinBox software in the past to configure a small switch, but my experience with it is minimal.

Can someone point me in the right direction?

They are point to point link devices so should just work.
These are much better suited for that purpose by the way.....
https://mikrotik.com/product/wireless_wire_cube_pro



Saw this on a search
https://mikrotik.tips/connecting-2-remo ... ss-bridge/

Also this
https://help.mikrotik.com/docs/display/ ... tion+Modes