When I was working at the Old Loop, I heard many times about a videographer who did just that. He was warned but insisted it would be ok .... to make a long story short, he lost his many-thousand-dollar professional video camera.
I have wanted to do the same thing for some time. Here's what I would do: Make a small plywood box for the camera, with the camera pointed up. At top of the box, mount a mirror at a 45-degree angle. Find a trestle and temporarily mount the camera box between the bridge ties with top (mirrored part) sticking up above the ties, rather like a periscope. That way, if something dig drag, it should only ruin the mirror. I haven't tried it but may do so one day.
Main culprits would be gladhands on air hoses, plus some engines have a low-hanging ash pan.
Skip Luke
Switchman (ret): Grand Canyon Railway;
Engineer (ret): Georgetown Loop RR Inc., Sumpter Valley Ry., Monticello & Sangamon Valley;
Dispatcher(ret): Illinois Central, White Pass & Yukon, Burlington Northern Ry.
Mariner, Musician, Miner