I'm towing a 9200lb loaded, 35 foot TT with an 02 V-10 X.
First off, if it hasn't already been done get a rear sway bar for the rear axle. Some X's didn't come with them some did. He ones hat didn't were plagued with wander issues due to the soccer mom springs Ford put under these beasts! Some people go as far as putting in F250/350 springs to help out with towing issues. I went with airbags.
The exhaust manifold issue is more broken studs than anything. I have 1 on each side of mine that are broken right now (going to do hose his winter).
Once setup to tow it is an amazing SUV!
As was said, check all maint. have the frt end checked out for loose parts. If it was truly cared for it will show!
I do several 10+ hour trips non stop (other than gas and bathroom) I've even done a couple 13 and 14 hour trips. Very comfortable vehicle!