The X will handle a 35ft TT without issue provided its setup properly (as with any vehicle). My X has 4.30 gears, airbags, Hellwig rear sway bar and a Reese Dual Cam WD hitch. I routinely tow 10 hours on traveling days, I have done up to 14 hours without issue other than being tired.
Have the X gone through for safety issues such as brake lines and hoses and front suspension. Not sure on the miles of your X but depending on what has been done get all maint. up to date. including all fluids. I carry 2 extra COP`s (ignition coil) with me. I replaced my fuel pump when I replaced my trailer hitch. Right now as I know of Curt is the only one offering a hitch for the X.