I had a TT and a 5th wheel. I see you have a dually and honestly i don't think you will see much in the difference between a 5er and TT in wind with your truck. Now if you had a SW,SB yes without doubt you would notice. The height of the 5th wheel gets to be a pain. I have broken my skylight twice and knocked off vents multiple times with my current 5er. None of that happened with the shorter TT.
I could go on and on but what made me pick the 5er over another TT was the under storage. No comparison between the two.