I towed a 5,000 lb trailer from NJ through SD, WY, UT, CO and back with my V6 Pathfinder SE. I also had 600 lbs of people plus another 250 lbs of gear in or on the truck. I had no trouble except for the expected poor fuel economy and being a bit underpowered going up mountains.
You will have to deal with some mountains going through PA. My recommendation is to allow your speed to drop rather than attempting to drive at high RPM for extended distances. This not only saves wear-and-tear on your engine and transmission, but will help your fuel economy.
Check with your trailer rental company about whether you need a brake controller or not. Towing more than 1,200 lbs will require some kind of trailer brakes, the most common for rental trailers is hydraulic surge brakes, which require no additional equipment. The force of the trailer pushing against the hitch coupler causes a piston to activate the trailer brakes. The disadvantage of this system is that attempting to back-up over unpaved surfaces or uphill also will activate the trailer brakes.
Electronic trailer brakes do not interfere with backing-up and generally allow finer control of trailer braking forces and manual activation of the trailer brakes (useful to control trailer sway). But this system requires the installation of an electronic trailer brake controller and a new hitch wiring connector to interface the trailer's electronic brakes with your vehicle's braking system.
If you do need an electronic brake controller, I recommend you DO NOT get one from the trailer rental store. When I looked around, all the trailer rental places wanted to install a cheap brake controller and cut into the factory wiring harness, rather than go with a better (but more expensive) proportional brake controller and use OEM wiring harnesses. If you need to use electronic trailer brakes, look around this and other forums for what others have done, or post a follow-up question here for more information. Installation is a fairly-easy do it yourself, plug-n-play project, with the only problem being locating a suitable place to mount the controller within easy driver's reach.
Since you will be towing more than 5,000 lbs you will need a weight distributing hitch (WDS hitch). This should be supplied by the trailer rental outfit, otherwise you're looking at a minimum of $400. Ideally, the WDS hitch will also have anti-sway features (friction bars or pistons).
You should also take time to review the [url=http://pdfcast.org/download/nissan-towi ... e-2007.pdf
]Nissan Towing Guide[url] for some generic but helpful information about towing.