A couple of comments from my experiences with grizzlies in MT on the front range. At night, you aren't going to catch it coming in from any distance that you would feel safe. They are silent in their approach. Their eyes don't tend to shine much either. A buddy acting as a sentry will likely just exclaim "oh shit! there's a bear!!". And the bear will already be feet away.
Talking, singing, etc work to keep bears at bay better than other things. Even if you sound like an idiot talking to yourself or can't carry a tune in a bucket. Remember the bear doesn't necessarily know there is food there. Human presence is usually enough to keep them away for a time. Figure you have that night, and have to get that elk out the next day. Most bears are not habituated, so let them know you are there and they will leave you alone.
Don't spread your stuff out. Keep your pack and rifle ready to just grab and leave with. If a bear approaches, grab your stuff and go, if you can grab your stuff. Either way, back away slowly, but purposefully, and let it have the elk.
You should be far more worried about retrieval later on. I would NOT recommend packing it all out that night. Take a load out, then go back in the daylight. Why risk walking into a bad situation at night? Go back in the daylight, get upwind so the bear smells you, get eyes on the quarters from a distance away and assess the situation.
My last comment is to get it done fast and only do what needs to be done. If gutting it is enough, just do that. At night you are at an extreme disadvantage. No need to compound it with time spent in the woods. Throw a hat and a few stinky clothes on it and hope for the best in the morning.
Jeremy