What is the purpose of the code for where the cord enters the vehicle? I am planning on mine exiting the first bay on the left side and I don't see what difference is made by the cord being nearer the front or rear. Usually the codes make sence, this one I don't get.
Well, first let me say that this provision of the code, and many others, are intended to protect the end-user of an RV from poor design on the part of the manufacturer. Without such code articles, manufacturers are wont to do some pretty stupid things.
In this case, the issue is that RV parks are mandated (by the very next chapter of the code) to put the power pedestal at rear of the coach on the driver side. The idea is to try to standardize where both the pedestal and the inlet end up, so that normal-size cords will reach.
If you build a 40' coach, and put the power inlet three feet behind the front bumper, then you'll need, on average, a 40" long power cord to reach the pedestal, which can be expected to be right at the rear bumper on the driver side. Most cords are just not that long, leaving the RV buyer up a creek.
In the current version of the code, a manufacturer is actually permitted to do this, but he then needs to supply the customer with a 47' cord as well (37'-15'+25'=47').
If you mount the power inlet within the rear 15', you can supply the minimum-length cord of just 25'. RV builders are all about minimizing their costs, so they are highly motivated to put the inlet where the code specifies.