Changing Our Routine
After fighting the back harness for days, I decided to do things differently. Instead of putting the front harness on first, I put on the back harness first.
Man, this made things so much easier! Because her inclination is to lay down once I get the front harness on, I was able to do the back and then adjust it while she was laying down. Then I slipped over the front harness.
A little treat got the cart hooked up to the dog. This took less than five minutes. Less frustrating for me and less stressful for her.