I think it is unsafe to ride unbelted in a trailer or motor home regardless of their construction or the state law. Some may want to rationalize the unsafe behavior by claiming better suspension systems and the ability to communicate to the unbelted person but the fact is it is unsafe. to the point that someone may die. That is serious to me. In any accident I was ever involved in, the only words I was able to say was "Oh S**t! Think about it... "Oh S**t", does that give the unbelted person enough time to sit down, belt themselves in, and say thank you?
I don't want to sound "preachy" but when it comes to safety, rationalizing unsafe behaviors will cause injury and/or death..that is a fact. Just because a law says it is OK doesn't mean it is safe...it just means it is legal. One can always rationalize unsafe behaviors and convince themselves it is OK but should this forum condone behaviors that are unsafe? This forum is emphatic on their tow capacity position, and rightfully so. Thou shalt not exceed, in fact, you should be 10-20% under gross limits. Some try to rationalize their reasonong for challenging the Forum's position by claiming they have better braking systems, they have added air bags, a better suspension, bigger wheels and tires etc. but they are quickly admonished for their unsafe reasoning.
For those who rationalize this behavior is OK to do in a motor home but not as travel trailer or vice versa, remember you can't control when your tire will blow, when someone will pull out in front of you, or you swerve to miss a deer. Anyone not belted will likely have an extremely high probability of being injured. Take 5 minutes for the potty break or to put the pot roast in the slow cooker...you will get there at 5:05 instead of 5:00, and you will have a higher probability of getting there.