I'm pulling a 30' xlite that grosses at 7800 with a 2006 expedition with tow package rated at 8200 max trailer wt, I have a equilizer friction sway hitch, although not done much pulling with the new set up yet, I dont think sway is gonna be a huge issue, but I drive carefully.
In the past I pulled a rig the size of yours with no sway control at all with a ford ranger.
All being said, no such thing as too much sway control,
especially since it is gonna be you and your family going down the highway, not some salesman,
One experience with the trailer pushing you around at 65 mph with the wife screaming and kids crying will make you wish you'd gone with the best sway control you can get.
Besides if it was too much for this rig, it will be just right when you up size
2006 Expedition 4x4 w/HD tow package
5.4L 4 speed auto w/OD 3.73
tow rated 8200
2008 Cougar XLite 30FKS