Nada problem.
There is NO inductive/magnetic related heat buildup. The current flows in opposite directions (alternating at 60 Hz) on the hot and neutral conductors and the magnetic fields cancel each other out. The heat is caused by mutual heating of the conductors from resistance of the copper conductors. If cables are coiled in a tight bundle, there is no air flow and the coil will heat up. The plastic conductor insulation and overall cable jacket insulates the cable and doesn't allow heat to escape.
Estimating the heat generated by a coil is straightforward. Say you had 30 amps flowing through a shore power cord and there was a 10 volts of voltage drop across each end (starts at 120V at source and ends up at 110 at the RV), Ohms law would say you have 30 x 10 = 300 watts (P = V x I). That is a LOT of heat in a confined coil of cable.
HOWEVER, the reality is, there is not much voltage drop in a 25' (or 50') length of shore power cord. If you had 30 amps flowing through a 25' #10 AWG cord, the voltage drop (starting at 120V) would be approx. 1.5 volts and the heat generated would be approx. 45 watts. In a 50 amp 25' cord carrying 50 amps, while the current is more, the heavier gauge conductors have less resistance and the heat generated is about the same amount. RV shore power cord is normally type STW (thermoplastic) rated at 60C (140F). For higher rated temp., you'd want rubber-based type SOW rated at 90C.
While 45 watts isn't insignificant, unless you had your shore power cord wound up tightly in a small dia. coil and it was inside an insulated box, there is nothing to worry about. If you are plugged into a pedestal you aren't going to have a 25' cable fully coiled up. If damage from overheating shore power cords was a problem, you would find reports and warnings on the internet.
FWIW, in wood frame buildings, when installing romex/loomex cables you are not permitted by code to have more than 3 2-wire cables through a hole in a stud to prevent the chances of mutual overheating. For techies, here is a study showing how much cables can heat up in wood framed buildings.
Overheating study.Many ordinary household extension cords and appliance cords (space heaters, ex.) are only 16 gauge and these are a significant fire hazard if coiled up or hidden under a carpet. This pic shows damage to a carpet in an RV from a coiled 15 amp cord. Overheated cords in houses is the #1 cause of fires in the winter.
