Hypoxia: I don't see why you do not believe this. I have had a 10 year on my MH since that rule changed. About 2010. You can chose to believe what you want but the rule is the rule. I would not want to be stopped without that TIP. I asked the question in Spanish and English as he could understand English but not speak the language. He stated that cars and trucks do not need a TIP but RV's are a special category. I wish I could find the discussion from 8 years ago. Someone explained the whole thing: RV's, quads, boats, utility trailers and more. Some needed a TIP and some not. If you doubt this just stop at 21 and ask.
Moisheh