Debbie
I can help you with part of your question...We also have a 305SKP that is the same year as yours...I can tell you that you can put a fireplace in the area below the television because my DW and I took one out of that space, as our preference was more storage...Also the fireplace was extremely noisy and in our opinion did not operate that well...As far as the area behind the television, I know there is wasted space back there, because we owned a 30SK before our current camper and that area was all open, due to the fact that flat screen televisions were not standard issue in 2007...With that being said when we took out the fireplace there was a wire bundle that remains exposed in that area due to the fact the workers at CR saw no need to route the wires differently as they would never be seen due to the fireplace...Hope that helps you somewhat...