Looking for the Board's blessing, no WDH...

Have completed a single 350 mile trip with our new 2720 TM (reported specs: tongue weight= 346 lbs, dry weight of 2742 lbs). TV is a 2005 Pathfinder, 600 lb tongue weight and 6000 lb tow weight capacities. SUV is rear wheel drive. Rear tire wells appeared to deflect about 1-1/2" upon loading. The mechanics at the RV dealership were split on the need for a WDH. We made it back home safe and sound and didn't detect sway or bouncing (outside of hitting highway bumps at 70 mph). From the little I could read with the Trailmanor and Pathfinder manuals, it looks as if rear-wheel drive is beneficial and I don't need a WDH till I hit the 500/5000 lb plateau, respectively. Am I OK to go without a WDH?