Many jets have tire temperature displays. My recolllection is that the tires typically are not below 0 Celsius during cruise so they might be adding a slight temperature modulating effect to the wheel well temperature.
Are you sure you don't mean
brake temperature?
On Boeings these are shown as a 0~9 scale. On one aircraft type, "0" represents 176C or less (including minus zero C values). I recall that, initially, heat from the wheels may be a danger to stowaways, but this effect won't last long. The wheel well doors are not exactly insulated and seals are usually less than perfect.
I'd be interested to know if TAT or SAT would be more indicative of temperatures in the wheel wells.
Some wheel wells may have an extremely hot, uninsulated APU bleed duct running through them, but the APU won't be running for long after takeoff. Once the APU is off, the APU bleed duct valves will close, and there will be no hot airflow going through the wheel well duct. These ducts are probably more likely to injure the stowaway than protect him/her.
Comparing temperatures in the cabin with loss of airconditioning/pressurisation (due to pack failure) to temperatures in the wheel wells is probably not a good idea. The cabin is well insulated and full of heat generating devices: lights, electronics and, of course, people. People are natural heat generators.