I have 2 neon tubes under the dash (one driver one passenger). It was kinda tricky to get them mounted, but I just used the screws that came with it and put them as far up as I could fit them and screwed them in. They never move, and you have to stick ur head under the dash to be able to see the tubes. It glows really nice. I also have 2 LED projectors mounted up by the O/S bars and they point backwards which makes the whole back of the car blue. What I did for wiring them all is i got one of those cigarette lighter ports (the 4 port one) and plugged the tubes and the LED projectors into that, and wired the port up to the fuse box using the "add-a-circuit" wiring kit I got from autozone. That is probably the easiest way to wire something up.
As far as hiding the wires your talking about running to the back of the car, just run them under the door sill protector things like where you would run an amp wire.
I'm about to wire up the vent lights. Best way to do it is on focushacks.com ... just take out the vent pieces, drill into them and superglue the LED in. Go to autozone and get the thing called LED accent light kit. They are already wired with resistors and its real easy. 3 come in a pack and its 10 bucks a pack. I got 2 packs, I'm just gonna keep the other 2 LEDs for back ups incase one breaks. Anyway if you take all of your vent pieces out you can just run the wires inside behind the dash if you have long arms. Just wire them up to the switch and run another one of those add a circuit and you have your fuse and your switch. Then just wire the ground up to somethin metal and you should be in business. The switches I got cost like 2.99 a pieces and I think the add a circuit is 5.99 or 7.99. If you need to extend the wires, I'm pretty sure they are 24 guage. I dont think I will need to extend it, but if I do I am just going to cut the LEDs wires in the center and add wire to it. Thats how I had to do the projector lights because I tried wiring them up to 14 guague and they blew :-)
If you have the original wire coming from the switch and you add in some high guage wire I dont think it will affect it because of the original wire can only handle so much power.
Anyways, there's my directions. I would also recommend mouting the switches into the little fuse box cover thing by the driver door (the door that pops off) that way if u mess it up or u wanna get rid of it u dont have a big hole in ur dash..just a inexpensive fuse door.
I'll post pix when I get done next week. I'm in NY right now, but I'm gettin back on Monday. I'll get the pix up ASAP. Pm me if u need more help. Peace.