The Nissan Path

At about 42,000 on my 2012 R51 Pathfinder I am going to have my local auto shop do a trans flush, front and rear diff, transfer case, and rear diff fluid change. And I was wondering since I tow a 5,000 lb camper in the summer should I request a synthetic diff fluid to handle the extra heat the diff will see from towing? I am also going to have them check the brakes since they have never been checked. Can anyone suggest anything Ellis to check or replace at aprox 42,000? ... Air filter is new.

Nissan specifies synthetic gear oil in the rear diff, but not the front (however, you can use synthetic in the front, too, if you wish).