We have a hitch for our 20ft boat. We have a truck camper. Now we're buying a hi lo, new 2008 28c. Our TV is a 2007 Silverado 1500 HD. Friends have told us we need sway bars and torsion.

You need at least a Class 3 receiver on the TV. Hi-Lo strongly recommended a WD ( weight distributing) hitch, Check the manual. Some have the sway control built in, others it is a separate piece. I would also say that for safe towing a WD hitch is needed. If it was a 1 ton dual wheel TV then probably not needed. Some people tow trailers with out it, but you also see them fighting the wheel when large vehicles pass them at high speed. Your trailer weight is over 4700 lbs.
This is just another point, trailer tires have a max speed rating of 65 miles per hour.

I think you would be wise to go with a WD hitch and sway control. That unit has a 850# hitch weight before adding any options, water, gas, and cargo. I would go for a Reese Strait-Line Hitch, it has dual cam sway control built in. You will need 1200# bars. There are a couple other brands out there but that is the only one I have had experience with. With the WD hitch the weight is distributed between the truck and the trailer making everything level and it helps to maintain the weight on the truck's front wheels for better steering.

Also, get a good brake controller like a Tekonsha Prodigy.

Hopefully you will get some more suggestions.

I would strongly suggest a weight distribution hitch and swat control. I have a 2007 28 ft. Classic and was trying to tow it with a 1998 F 150. It had towed my 27 ft Towlight ok (with weight dist. and sway control) but did a poor job with the slightly longer and much heavier 28 ft Classic. I bought a 2007 Chevy 2500 and all my handling problems went away. I even quit using my sway control. So your trailer may be a "handful" for your half ton truck to tow. Mine could pull it ok, but semis would "push me around" when they passed me.