Okay, I think to answer my questions I should give a quick background..
I just finished fermenting a 5gal batch of porter. My plan was to bottle half and keg the other half. I was going to siphon half into the bucket with the priming sugar (half the normal 1 1/4 cup, or 5/8 cup extra light dried malt extract) and bottle that. The other half was going into the Corny keg; I usually force carbonation for 3 days at 30lbs.
Where I screwed up: When I was siphoning into the priming bucket I accidentally siphoned the whole 5 gallons. So I had the full batch with half the proper amount of priming sugar. But thinking about it, I wasn't too far off from the ratio suggested for conditioning in the keg with the ratio of 5 gal > 5/8 cup extra light malt extract. This wouldn't be too terribly far off from 1/3 cup corn sugar since you would double the amount when using malt extract. So in the end the keg has 5/8 cup vs. the usual 2/3 cup dried malt extract.
So what I'm wondering is: do I continue to condition the beer 1-2 weeks like this? I've never conditioned beer in the keg, I usually force carbonation. Since the keg is only half full, is the air in the sealed keg a problem? Should I hook it up to CO2 and pressurize at dispensing pressure while it conditions?
Thanks for your time reading this and your suggestions!!