On the newer Rams, the stock intake system is good, but can be better. I definitely saw some improvements right away when I added my aFe CAI. Little better hp. Nice growl up front. And some slight improvement in the mpg, maybe .5mpg better. May get some improvement by just dropping in a better airfilter, but maybe not. Didn't try it so I cannot comment.
Also, I don't pull a trailer, so I cannot help you on that one. Sorry.