yep....I keep a couple of 4x6's under each jack to keep the extension short on them. You want some.....just not a whole bunch. I have a whole system down when I set up the camper to get it how I like it. We really don't have much movement in the camper when I'm finished. The key is to get some of the weight off of the suspension to take the spring out of it. I don't lift it in the air but I take a lot of the weight off of it. I also use 2 load bars under the king pin to help with front side to side. Unless someone is jumping around in the camper it doesn't move. I have 3 younger kids so jumping is a real possibility.
When you have kids there are certain things that need to be said that ordinarily wouldn't need said......"no jumping in the camper" and my favorite "do not slam the door entering or leaving the camper". That last one is a talk I've also had to have with my wife.