Shadow says...drumroll please...
It's a skewed Pratt truss!
The "What's here" button is pretty accurate at determining what company currently uses the line.
You're correct that SKOL/SK&O uses the line.
I just discovered this bridge thanks to Google Maps. I will let the railfans decide the appropriate company, although it might be the Southern Kansas & Oklahoma (SK&O).
It is probably a standard Pratt or Warren through truss. It is located just outside of the town of Elk Falls, which is known for a wrought iron Pratt through truss built by George E. King.