I don't have a tray on my TR-186 but on mine there is a kick panel where all of the electrical and fuse box is mounted to under the dirver's side console if yo remove it you will see that it is open to the front rod storage compartment. When I replace my electronics I took that panel loose to pull the wires for the new tranducer through found all kinds of stuff that slid down there like a never opened first aid kit, can of beanie-weenie's

. This is open to the slot running down the side of the drivers seat to the rear bilge area. Also you could remove the front deck console and look in there and see where the upper deck is. I'm sure it's like mine you can see it open and there you will see where the wires come from the rear bilge area also. Just a thought.