This isn't exactly an answer to your question about the power, but something else to think about...
Our dealer's service center made a big deal to us about not extending the slide outs if the unit isn't level. They said to always level up first and then operate the slides and that many of the failures that they see with slide outs happened when the coach wasn't level first. Keep this in mind if you're trying to operate yours while you're hitched to your truck.
As far as 12v power goes, my last truck (a 2004 RAM) didn't come with a Trailer Charge fuse installed. I had to add a fuse to that position before my alternator would run my trailer's 12v system.