[pektel]

All laminate woods currently available (that I've seen) are floating. They lock into each other, but are not secured to the floor/walls. The expansion gap will vary depending on type/thickness of laminate used.

I doubt a laminate floor will stiffen your exisitng floor, since it is not attached in any way to it. For that, you would need to go to an engineered wood, but check to see how those handle the temp/humidity swings of a camper.