Free Camper Adventure: Do these tip over?

The support point of the camper isn't any different when it's sitting on the jacks vs. sitting in a truck bed. It's still not supported any further forward than the front wall. The pivot point is till the same. If it would tip over on the jacks it would tip forward sitting in a truck. You could probably fill the cabover with your whole family and it wouldn't be close to tipping forward.
Structural defects, that's a different story. I have no idea how solid the framing is after whatever your camper has been thru.