Hardcandy,
IMO, if you can lower your tailgate without hitting the trailer, leave the stock one on and make full use of your bed cover. If you can't, you'll want one.
I believe you'll find connecting and disconnecting your trailer requires you to be near the tailgate so raising/lowering it should not an issue.
The only turbulence issue I've had was when I lost an empty 2.5 gallon plastic gas can due to it not being secured properly. I carry much in my bed and believe my Fold-A-Cover helps in this area.
Enjoy!