Nice work jrpoux. Clean design and install.
Over time as rigs get customized (electrically) there is a tendency (at least when I do it) for things to get a bit messy. "Tap the winshield wiper wire for power that is switched with the key", "there is a heater hot wire real near where you want that so just..."
Related to that is the tendency to leave something on without noticing or a switch getting bumped but not noticing, that sort of Murphy's law thing. I find that if I force myself to think of the big picture rather than treating each project as a separate entity I get better long term satisfaction/results. Toward that end I usually make up for a shortcoming of virtually all manufacturers by installing a really heavy duty 12volt wire (and ground) to a convenient location (or two) with heavy duty terminal blocks (fused, resetable breakers being so expensive) in plastic boxes (Radio Shack, like you). I like to fuse the heavy runs near the battery so in case the wire ever got hit, pinched, or whatever the fuse would blow rather than cooking the wire or starting a fire (been there, done that) as it would if the fuse were at the other end.
In some cases I have "gilded the lily" a bit by having two busses, one hot all the time and one fed from a 100% duty cycle rated solenoid with the coil wired to the switch. This way I have a choice of hot all the time or of switched power (but not taking the power through the little key switch contacts which won't take too much abuse for long).
So far I haven't done any electrical customizing to my litle Kubota L4610HSTC but I think it needs air horns, a couple two way radios, rear facing work lights, more cigarette lighter outlets (switched and unswitched), a lighted toolbox and ... and a cup holder and a fire extinguisher mount and........ Isn't that what winter is for? Time to customize your ride.
Patrick (impatienty waiting for the dirt to dry so he can tractor on)