I do most of the towing. During our two Disney World trips Wife drove for portions of that, sections of highway that were not crowded or in cities. No problems. She was nervous, but then said "That's it? that's what I was concerned about?", lol!
When I am towing, I do point out to her some of the things I'm looking out for - plenty of room for me to turn (takes a bit of practice to get used to crossing the yellow line into the other lane while turning if needed), watching speed limits, planning for lane changes, planning my route and gas stops. And DON'T blindly follow the GPS!!
As in other posts, you need to "back off" a bit and not over-teach someone, especially wife!