I've been using a tarp with hiking staff since forever. Love this arrangement, except when the bugs are bad.
What I've learned (the hard way) is to always, always use a ridgeline. There is no substitute.
On their own, tarps will sag as temperature drops, and as rain falls or wind comes up. The ridgeline keeps the tarp from slumping onto your sleeping bag (bad news, since the underside is pretty damp from condensation).
The ridgeline puts your support just outside the front of the tent, and you can adjust everything in the night without getting up. I always angle the stick/pole a little when setting up, so I can just reach out and move it later to increase tension on the ridgeline.
If you're having a lazy moment and don't want a ridgeline (you'll pay for that later) you can use a cup or canteen from your kitchen to protect the tarp. Though not in bear country.