Are you looking to sell additional assets in-area without affecting the fan experience? Have you considered selling your tunnel signage, where players and referees enter the playing surface?
I have attached a Calgary Flames 2008 commercial, which details the interior tunnel signage that the team incorporated with its Nike partnership (seen at the :09 mark in the commercial). As you can tell from clip, Nike does a great job branding the tunnel's interior fasica, driving brand awareness among all persons entering the game of play.
Now, you might ask, who would want to purchase this non-consumer-facing asset? I would think that there are many companies/categories that would be receptive to your sales pitch:
This asset can either be sold individually or as a complementary asset to the exterior tunnel signage (consumer-facing).