I'm trying to install a backup camera on a 2010 E450 Shuttle Bus made by by star Starcraft.
I would like to tap into the back up light signal somewhere in the front of the vehicle so I don't have to run a wire all the way to the back of the bus.

Does anyone know where I can find a guide or a user manual to help locate the backup light wiring in the front of the vehicle?

 

I don't have diagram for any 2009-up.
You might want to check your fuse box with one that's labeled something like "trailer tow running lamps and back-up lamp relays", then verify if reverse signal is present, you can then put the add-a-circuit fuse type adapter there. Or the relay box with "trailer back-up lamps relay".

Not sure how your Starcraft works. If it comes with cigar socket you might want to hard wire it. 2010 E450 I don't know, but the previous generation of E and F series, both power plug and cigar plug are hot at all times (not switched power). You just need to make sure it doesn't drain your battery when the reverse wire is not triggered, sometime when it's triggered it gets power only to your Starcraft screen display so make sure it doesn't draw any power when engine off key out.
Cellphone car charger for example, these days all of them will come with an led indicator, it's this little led that will drain your battery whenever it's plugged into the cigar socket, whether or not your phone is charging.

 

There's a relay in the battery junction box but you can get to the wiring under the dash on the driver's side. See attached wiring diagram and pinout and location of C263.

 

So Fuse 58 should work or at Splice S142.
If your Starcraft display can be turned on by itself without the shifting to reverse or you also want it this way so that you can see any potential pedestrian in advance, simply add a blocking diode (to prevent backfeed to turn on your reverse lamps) then a relay then the reverse trigger wire of your Starcraft.