Check out your local garden centre, Canadian Tire, farm implement dealer (there is a John Deere version), and for around $200 you can get a garden cart wagon that will be large enough for five. If you don't have the harnesses, you can rig a similar thing using bungee cords. It would getyou through till you get something else. Having that many in the cart will give them something to lean against if they fall asleep. Might also want to consider time of day for the walks and instead give them a nap and then go for a walk if they are falling asleep everyday.