SWD wrote:
We harness trained our cats at home before going away. Rusty, our old neutered tom, even gets to wear a life jacket when on the boat.
I would suggest doing exactly that. Working with them at home to get used to the harness can be the solution. Start them in the harness and teach them to take a step towards you with treats. One step at a time until you get them following you. After a few days to a few weeks, once you put on the harness, they should be willingly following you, expecting a treat.
Once you get them to the point they willingly walk on the harness around the house, you can start venturing outside in the back yard.
One last suggestion. Wear long thick pants in case you have them get scared. Nothing worse than a scared cat, wrapped around your leg on a leash. Tends to leave permanant marks.