Since we don't have the actual weight numbers, this is all just a big guess.
If the brochure base weight of 5530 is correct you'll need to add the weight of any options which may include the awning, AC, full propane tanks, battery etc. This usually adds about 300-400 lbs, so let's say your at 5,830 lbs. Now add food, clothing, towels, linen and so forth to the tt, which can easily be another 1,000 lbs, well that puts you at about 6,830. Close the weight that you originally gave us.
The brochure also gave a hitch weight of 740 lbs for a 5,530 lb tt. That's a little over 13%, which falls midway in the 10-15% recommended range. Using that ratio your tt's loaded hitch weight will be around 888 lbs. You stated your GVWR is 6,800 lbs. Subtract the actual loaded weight of the vehicle (including full tank of gas, passengers and gear) and that gives you what's left over for your hitch weight. Oh yeah, don't forget to add in the weight of the hitch.
If indeed your wheelbase is only 111", well that's just pretty short for towing a tt that size. A good anti-sway hitch doesn't make up for a bad set up. Maybe a Hensly would work, but they cost a few thousand dollars.
You also asked about add ons to your vehicle's suspension. No matter what you do, short of a complete suspension overhaul, you will not increase any of your vehicle's ratings. As mentioned in previous post, the 3:42 rear gears aren't very good for towing.
Like I said, this is all guess work since we don't have actual numbers to work with. But If it was me, I would look for another tow vehicle.
Gary & Trish
"PT Crew Member Since 11/2010"
2017 Prime Time Crusader 315RST TE 6.0 : 2007 Flagstaff 206ST MAC Series
2012 F-250 Lariat : FX4 : CC : SB : 6.7L Diesel : 3/55 Gears
2016 Nights Camped - 9