Some background information:
My buddy and I (both relatively new hunters) have been hiking in to an area for bears over the past 3-4 weeks, and finally connected on one last night around 6:30pm. Buddy took the shot from inside of 75 yards (aiming vitals on full broadside) and the bear took off into some really nasty thick stuff. We waited an hour before starting on the track.
The blood trail was good in the beginning - consistent drops on the ground, lots on pine boughs and tree branches etc. After crawling/bushwacking along the trail for about 50ft, we heard twigs snapping and something big moving away from us. We marked the spot and waited another hour.
Fast forward, and basically the same thing happened again - follow the trail, bump the bear after ~50ft. At this point it was about 9:00pm and daylight was fading, and it started to rain.
Concerned about losing the trail, we continued searching. At about 11:30pm, we came to a spot where we can hear heavy breathing and some rustling 15-20ft in front of us. Unfortunately visibility was basically zero due to the thick new growth and darkness, and we made the tough decision to leave the animal for the night rather than risk walking into an injured bear in close quarters.

This decision was made harder because we knew we couldn't come back the next day due to work commitments, but we'll be heading back tomorrow to try and recover the animal. We have the location marked, and the hope is it didn't move much further from where we last heard it. My questions for those of you with some experience:
1) What's the longest you've gone before recovering an animal, and how much meat spoilage was there? (Ours is in an area averaging ~10 degrees celsius and rain)
2) Is there anything we should do immediately to the meat to try and salvage as much as we can (ie. vinegar)?

I'm pretty torn up about potentially not being able to recover an animal, but we'll give it our best tomorrow.
Thanks in advance.