Yes, but the guitar generally played the role of bass instrument in Old Time / hillbilly music. I don't think there's anything wrong with using a stand-up bass when playing a contemporary reworking of the style. What about those tenor guitars that showed up on country recordings in the 1950s and 1960s? Or those twangy-sounding Danelectro basses? How do you draw a line between guitar/tenor guitar/'twangy' bass? The bass was there in Old Time music, how you achieve the 'bass' sound is open to interpretation.