Generally, I evaluate questions like this based on cost/benefit. Unfortunately, life is highly unpredictable . . . nobody really wakes up in the morning with a plan of being in an automobile collision that day. But, the fact is, each week there are enough traffic fatalities to fill a 737 and 10's of thousands of injuries. Last weekend alone, there were 6 fatalities in the Phoenix area.
So, as a parent, it is my obligation to do the best job possible to ensure my family's safety in case of one of these unanticipated events. For me personally (and we each must make our own choices), I believe it would be irresponsible and negligent in allowing anyone to ride in the camper (especially since its not designed with the safety of its passengers in mind) while barreling down the road. If you've ever seen an rv after a collision, you have likely observed that they pretty much disintergrate.
Agreed, it would probably be a fun and memorable experience to ride in the camper during our family vacation, but I would also live with the memory of my bad decision if someone was injured or killed in an accident. The benefit does not outweigh the cost.
Happy travels, have fun and be safe.