My Expedition: 2013, XLT, HD Tow package. Just bought a new travel trailer. It's a little bit heavier than my previous one (about 1,000 lbs heavier). I tow with a weight distribution hitch and the trailer wt. is 85% of the truck's tow rating. I feel like the rear suspension is not handling the tongue weight well and was wondering if there is an after-market way of stiffening it. Dealer says no, but I'm wondering if that's just because they don't add that kind of mods there. What's the word on this?