Oars

Hi all,
I'm about to install oarlocks on my DSII, but just realized that my mainsheet is mounted center boom with the tackle located on the aft end of the centerboard trunk.
I saw some photos of others with the same setup but I'm wondering how annoying this will be. Am I going to get tangled up in the mainsheet every time I row?
Also, I have a set of 7' oars that I would like to use, but I see most everyone is using 8' or 8.5'; Is 7' way too short?
I'm about to install oarlocks on my DSII, but just realized that my mainsheet is mounted center boom with the tackle located on the aft end of the centerboard trunk.
I saw some photos of others with the same setup but I'm wondering how annoying this will be. Am I going to get tangled up in the mainsheet every time I row?
Also, I have a set of 7' oars that I would like to use, but I see most everyone is using 8' or 8.5'; Is 7' way too short?