My experience with a 2003 F-150 at 0-500 pounds over GVWR and 3/3 ton Suburban well 500 pounds under GVWR are:
If a WDH is adjusted such that the front axle weight is fully restored, rear suspension aids are not necessary. there is more than 1.5" of rear suspension drop with the front axle weight restored, then the TV is overloaded. Even at 500 pounds over GVWR, my prior F-150 never looked overweight, no V-shape as some people call it.
Wait on air bags, overload springs, etc. Spend $15 at a CAT scale to understand your true weights and how well that WDH is adjusted. Read the link Barney provided on how to adjust a WDH. The so called experienced RV dealer/service have a lot of complaints from owners with regard to WDH adjustment. Between not adjusting correctly up front and owners changing the tongue weight, many TT owners experience poor stability due to poorly adjusted WDH.
jaycocreek wrote:
To each his own. I pull a 10K wood trailer without a WD hitch and the air bags are one of the reasons I can do that besides other mods. It pulls just fine.
Air bags are not a replacement for a WD hitch but are a huge improvement over the factory setup. I regularly pull a heavy tongued 24ft Security travel trailer workout a WD hitch.
Your receiver is not rated to do that. Neither was the truck designed to do so. You are likely exceeding the rear axle as well with both trailers. Rear suspension aids tend to mask these overloaded situations as you say, it looks and tows fine.