Flight Instructor reported a confusing taxiway configuration near the approach end of Runway 31 at CVH airport needs better signage and as well as clarification on an airport diagram.

Narrative

At Hollister airport; we were taxiing from the FBO / apron to Runway 31 for run up and departure. My memory of Hollister Airport is there was a long displaced threshold for Runway 31; so I intended to use that entire displaced threshold distance for takeoff (and for demonstrating a soft field takeoff). We taxied from the apron via the apparently-unnamed diagonal taxiway. Eventually that taxiway intersects taxiway A; then turns and becomes a taxiway in the approach area of Runway 31; aligned with the extended runway centerline. Either the hold short bars do not exist or are worn or faded; or in any case we did not see them; and as we continued to taxi realized there was no displaced threshold; and the taxiway was actually in the approach area of Runway 31. We stopped before making the turn to align with the runway; did a quick pre-takeoff check; checked for traffic and communicated on the CTAF; taxied to the threshold; and departed; but it seems ultimately we should have been holding short of the approach area at some other point that we never saw and had inadvertently taxied into the approach area. Although we stayed outside the area aligned with the runway; this presents a hazard when an aircraft is on final; and indeed an aircraft turned final over us as we performed pre-takeoff check (in my estimation with sufficient separation since it was landing well downfield beyond the threshold of Runway 31). There is no mention of this odd configuration in the chart supplement; although the notes do say takeoff is recommended beyond Taxiway B. There are no NOTAMs relating to these taxiways; and there is no FAA airport diagram and no hot spots defined for the airport. I feel that this area should be a hot spot given its confusing configuration and the risk of runway incursions; and it should be confirmed that the hold short bars for 31 / APCH are clearly visible from all areas where an aircraft could taxi; and/or that closed taxiways are clearly marked.