Just back from a few weeks camping in Yellowstone/Teton bear country, with Counter Assault large (primary) and small (backup) spray canisters unused, and Underwood Extreme Penetrator.44 Mag. rounds unfired from my S&W 69, (thankfully, at about $50 for the spray canisters,and $2/round for the ammo), with the following observations --- You can rent bear spray, and trust some underpaid, overworked, unconcerned, temp hire for its ultimate efficacy, but, I'd buy new... In any case, I'd recommend using an inert training spray to test/inform yourself about the spray's behavior, before you need to deploy it --- its mist rises very quickly, and is diverted by a very slight breeze, so, you need to position the wind at your back and wait until the very last moment, and aim the spray very low at an attacking bear, or you'll overshoot, ineffectively, and suffer the consequences, long after using a gun was an option (except to put yourself out of your misery...)..
I found that an unobtrusive/unalarming/apparently unnoticed way to carry both a fairly large revolver --- S&W 69 --- and bear spray in its holster, was to carry the gun in a Wilderness Safepacker holster in that company's "Packer Backer" holster belt, with the Counter Assault spray holster hung on the Packer Backer belt. If anyone noticed the gun, I didn't, and one nite, in the Tetons, a stir among the campers alerted me to the presence of a bear in the campground, which I pursued, and hounded, and shoo'ed away from the campground (I thought), hoping to discourage its unwelcomed behavior, only to learn the next morning that it was tolerated, deemed "harmless" by park officials and not regarded with much concern... So much for the "bear scare" drumbeat of the Park Service...