There is logic behind the rules in the NEC. Lots of smart people from many professions have collaborated to develop it over many many years, and it has avoided countless fires and saved countless lives. You can do whatever you want of course but just know that in doing so you are assuming you know better than all those experts.
In this case the logic is that by placing all disconnects, switches, fuses, and circuit breakers in the ungrounded (positive) conductor you can count on the circuits being dead when those devices are open. If you put some disconnects one line and some in the other it is very easy to inadvertently get current flow when you don't expect it.
There is nothing "iffy" about the applicability of the NEC to RV's because of jurisdictional differences. The Code gets updated every 3 years and then has to be adopted by each authority having jurisdiction. So you can find one AHJ on one cycle and another on a newer one.
But, keeping the neutral connected and grounded and switching the hot conductor has been in the Code from before anyone on this forum was born, it is fundamental to electrical safety strategy in North America. The only exceptions are some industrial applications where the equipment won't work properly unless its on a floating circuit, and then there has to be special ground fault detection equipment in place. So, no matter what jurisdiction you are in and what code cycle you are on, you are non compliant if you are switching the grounded (negative) conductor.