I have powered lights and fans to a reciever. Fans are easy lights tho...can be frustrating. 2 ways one way is with the box. It's the hardest because most boxes are many to control the lights with your servo and esc...brighter fronts when driving dimmer when stopped reverse lights and signals....can get finicky easily after bad landings too because of servo maybe getting off center... 2nd way is skip the box and wire it directly to your battery or 3rd channel on the rx...wouldn't do more than 10 leds assuming each uses about .5amps draw back is your body will be kinda connected to the truck...
I like skipping the whole deal and wiring a 9v to the body. I find it to be the least problematic.... I'll explain, the granite has kinda a limited battery area. To run stuff takes amps... A batteries
mah(.01) x c rating = amps
The more mah a bat has the longer the bat is. The more c rating the bat has the taller the bat is. Without any fan and lights...winch....whatever....just to run a 10 scale takes about 90-95max amps. You will want to take that in account if you set up some lights and a fan which will make the system need 105a max
So say you get a 4000mah 20c lipo
4000(.001) x 20
4.000 x 20
80amps max
I been going through this because my system needs 95 max amps and my battery has suffered
Thankfully I did see someone say there was an smc battery that's 4300mah 40c
4300(.001) x 40
4.3 x 40
172 max amps
Figured I'd give you some thoughts about the subject
Even when I do switch batteries I still won't do it because I personally would find it annoying to take off my receiver box top so much...especially after trying to fit more connections in that tiny box