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disclaimer: I have enough knowledge to be dangerous, but not enough to be an expert.  That means don't hold me at fault for anything.

Some very expensive RVs have cord retractors so they definitely have a concern with fire due to an only partially extended shore power cable.

The reality for the rest of us is that this is absolutely NO concern.

warning: slightly technical explanation below.

The concept  is that an energized electrical cord that is wrapped up becomes an inductor.  Inductors generate voltage, heat, and magnetic fields.  Left long enough, lots of heat is generated, the insulation will melt, eventually shorting the wires and causing a fire.  Additionally, the excess heat causes a reduction in resistance in the wire, also increasing current, and thus heat as well.

This is a real and genuine concern in any cable that is wrapped in a mostly circular fashion.  i.e. If you wrap a cord around your arm, drop it to the ground and it lays down mostly circular, run a 1500 watt heater through it for 8 hours, guaranteed fire hazard.  Just grab the loop of cord and see how hot it is.

Most travel trailers have a hidden compartment with a hole where you pull the shore power cord out.  When you push the cord in, does it loop up in a perfect loop?  No.  It goes in like an absolute mess going left one second, up the next and who knows which way the second after that.  There's no opportunity to create an inductor because any magnetic field is cancelled out by the next cable crossing at an odd angle, repeated a dozen times.  (I've even had mine knot up inside that box, yeah, not fun in the field.)  Even full current, continuous use (24A >3hrs) is unlikely to pose any threat.

I have had an extension cord nearly cause a fire in my house, caused exactly because I left the excess cord wrapped around a circular cord loop.  Those cheap cord loops that look like an H, not really a threat if you leave the excess cord on.  Additionally, this is only a concern with continuous use.  If you are using your corded drill to make a dozen holes, you don't need to stretch out that 100 ft cord to do it, use what you need.

Good info to know: electrical code says continuous use is anything >3 hrs.  It also says that during continuous use, you cannot exceed 80% of the rated amperage.  So a 30A cord can really only draw 24A continuously.  An example: if the AC 15A, and the microwave is 14A, you can run the AC continously and still use the microwave for the 5 minutes needed to cook dinner.  Your continuous use is 15A (<24A) and your non-continuous rating is 29A (<30A rating of the cord and system).