Just came back from our first trip in a new-to-us 1982 Coleman Sun Valley. Great time but one thing we noticed is that the camper was very bouncy. Whenever one of us would change sleeping positions, or our dog would pant on the floor, etc. the whole camper would rock. This is the first popup I've owned so maybe that's completely normal...and it's really not a big deal. Maybe we just need to go on a diet Just wondering if this is normal/to be expected or if there is some trick to minimizing bounce?