Agree. Pop-up, or hard sided trailer, or MH, no different than at home.
If the kids sleep with Mom and Dad at home, they'll be sleeping with them in the camper too.
Keep them in their beds? Probably won't happen. The secret to our success was to run the kids so hard all day (and do not give them naps in the afternoon... NO, NO, NO!!!!!) That by 7 or 8 pm, they literally fall asleep anywhere (IF you can get them to stay still for 15 seconds!)
My grandson is now 4 years old. He and his daddy (my son), live with us. We're going through the exact same thing! The secret is .... NO MORE NAPS! Keep them awake! And then YOU can sleep at night!