I've had a quick fiddle with LDD to see if the fronts can be lit and reckon I've got a pretty good run from the IR to the front under the battery pack. It is a tight fit under the battery, but the small cables should run under like they do in the passenger train. I'll post an update when I get round to ordering the light set (all my others are being used and a hassle to rip them out to try).
The front method is pretty much the same as Homer's idea though when it comes to the light sections. I've kept to the official dark grey centre block between the lights though rather than red like homer has done.