One thing you won't be able to see at this point is how very difficult that area is to access with all the trimmings installed. Anything forward of the first bulkhead on the floor or further up is almost impossible to reach, especially when the rudder pedals are installed.
Like others have mentioned, most of your wiring has to go to the instrument panel and running it up and along the sidewall is probably the best installation method.
Trim wire bundles from elevator and wings along with AP wire bundles.
ADAHRS wire bundles and lighting from the wings all terminate somewhere behind the panel. You wouldn't want to run those under the floor and up the firewall. Probably won't hurt anything to have that battery cable where it is but it sure looks inconvenient to me.
Furthermore, having a solid battery cable run lends itself handily to attach other wires to it.