I had a 22' awning on our HR. It didn't have a center awning rafter/ground pole and one "strong wind" lifted it and buckled the awning tube. The RV was new then, and it was covered under warranty, but while they were installing a new tube (over $300) I had them go ahead and install the Carefree center support/rafter/ground pole. It cost about $85 back in 94, now it's $166.39 and here's the link for the complete assembly:
http://www.campingworld.com/shopping...-carefree/7860
You can get just the upper (under the canvas) part separately, for $119.59 at this link:
http://www.campingworld.com/shopping...-carefree/7859
If I were you, I'd go ahead and get the ground support also for the extra 40 bucks. It all attaches to the side of your RV, supports the tube during travel, then opens with the canvas, tightens against the roller to keep the canvas tight and also attaches to the side if the RV (like the end supports, or attaches to the ground to give a bit more room. If you've got the automatic awning, you'll have to deploy this support manually, like on the old awnings, but if you have a manual awning, it's just the same procedure as your other tow supports.
Hope this helps at least a little.
John