Have a look here
Not the best pics, I can try to put some more up for you, i've got plenty that will show the area you need, also have a drawing which shows the layout.
Has Chris given you a copy of the build manual and the drawings pack?
I think it's only the brake pipes that need to be clipped every 200mm for IVA, not sure they're fussed about air con, heater etc....
I think the cable tray might be a bit OTT, it will also make it tricky to maintain afterwards, as the gap between the body and chassis isn't too big.
So long as nothing is sticking outside the top rail you will have no problems, there is a fair bit of space in the sills.
Passenger side - wiring loom, two heater pipes, two vacuum pipes, battery cable, brake pipe.
Driver side - air con pipes, two large power cables for other things in the car.
Centre - Accelerator cable, gear change cables, brake pipe.
Hope this helps, feel free to email me if you need any help or other info.