So these guys are 34" high. Googling ohter 34" horses, they weigh about 150. 300 lbs together, can pull 900 to 1500 lbs.
My estimate-
Red shirt tubby: 300 lbs Cowboy hat guy: 200 lbs 2 girls back left: 100 together Darker girl behind RST: 75 The three remaining children: 150 Cart:200 And how many children hanging off the other side? We are still under the limit...