Robert, stop. Pump the brakes...figuratively.
First, your "upgrade" to a newer (presume relatively newer) Pathfinder isn't much of an upgrade for towing ability/capacity, at all. On paper, yes, but it's not 6klbs if it doesn't even have a trailer hitch.
I mean, it's "ok" but are you buying for now or buying for your future plans of alot of trips and several x country trips a year? Either way, it is a less than ideal vehicle to tow a full height trailer anywhere but shorter trips, especially long grades and altitude.
IMO, either commit to buying a tow vehicle or just run the old Acura and save spending needless money on not much of an upgrade.
And get a real, hard wired brake controller. Specifically since you don't know much about towing. If the vehicle you're towing with isn't pre-wired for brakes and sporting a hitch receiver from the factory, you're sort of throwing good money down the drain.