I might agree with you if you could show us proof of someone actually being found liable for causing an accident with bodily injury when a tow vehicle was overloaded WHILE TOWING A RECREATIONAL TRAILER.
I did post a link to one a few years back. Can't remember the details now but anyone can file a civil case and you only need preponderance of the evidence, not beyond a reasonable doubt. Much lower bar. Not hard at all to imagine a jury finding for a plaintiff when a family member was killed for someone being overloaded. I'm sure there are many cases. I did a quick search and found and posted 1.
I agree with you that the odds of getting pulled over by local police or DOT towing recreationally are slim to none. But in a civil case even if you win it can bankrupt you.
I remember seeing that post.
The problem with finding the evidence to back up the claim is that you would have to search through EVERY civil court system in the country, of which there are a LOT, and not many people have the time to do it. From what I understand many of them are not easily searchable (I do not know this as I have not tried). It's public record but public records are notorious for being hard to search unless you've got something specific.
THAT SAID, looking at the laws as written, and having a basic understanding of how insurance companies work and how sue-happy people are in this country, it's not much of a stretch to see that the possibility is there. It is VERY true that LEOs very rarely enforce loading or limits on personal vehicles or RVs unless there is an OBVIOUS situation, but all things considered they easily could enforce those rules and laws. They are written to specifically apply to commercial vehicles or 'for hire' vehicles, but they're still a good guideline for personal use as they're written with safety in mind, and it would only take a few word changes for them to 100% apply to personal use. Is it likely this will happen? I'd argue no, but the possibilities are there.
In the end, it all comes down to the risk people want to take. Personally I'd rather not gamble with mine or someone else's life, I'd rather not gamble being sued in civil court and possibly losing, and I'd rather enjoy my time on the road as much as possible, given how many idiots are on the road today. If YOU are willing to risk your time, money, and life, by all means go for it. However, it IS a risk, and it SHOULD be pointed out to someone new to towing - if you are overloaded and end up involved in an accident, you risk being held liable. Will it happen? I can't say. Could it? Absolutely.