Speaker Wiring, One side of the trailer to the other Options

[Tamid]

I have a 25" FB Bigfoot. The CD-DVD and speakers are above the dinette on the driver side. I would like to put more speakers on the passenger side. It seems impossible to run wires through the ceiling so I'm wondering how I would run them through the floor and if I need to get into the basement i.e. holding tank area to run them. Any ideas?