Doglips

OK, 3 kinds of heat transfer.
Radiant ( the sun's rays makes pot hot)
Conductive (hot pot makes soil hot, makes roots hot (touching))
Convective ( using misters to make cool air to replace hot around the pot)

If you are cooking the plant above ground, in or out of a pot is not relevant.

If the temperature outside is 100F then your roots are 100F (at least). Deal with it.

Misting (essentially convection)
Evaporative cooling's (misting) effectivness is realtive to ambient humdity in the air. Low humidity means good evaporation and thus cooling. If you live in sticky Florida, ain't gonna help much. If you live in Phoenix, big help.
Air misting can help pots, a little. Cooler air passes by the pot, the air wicks away a little heat from the pot. If you can lower the outside air temp then you will lower the pot temp. As far as cooling the roots go, you would be far better off by watering the outside of the pot, a greater potential for evaporation.

Conduction
One hot object touching another object to make it hot. Placing a pot on blacktop equals roasted roots. A pot on wet earth can help wick heat away.

Radiant ( The big one!)
This is what this thread is about. Convection and conduction strategies are about trying to win a losing game. Removing the radiant threat gives you a cool pot to begin with, as opposed to trying to cool the hot pot. In short, keep the sun off of the pot. Light does one of two things when it hits an object. It either reflects or absorbs (refracts). Lighter colors are more reflective. When light gets absorbed, thats radiant heat. So, a light colored pot is good. So is wrapping it in a light colored fabric or aluminum foil (aluminum foil is champ, just looks like crap), as is painting it (careful with this one). Placing an object between the sun and the pot is a big help (just the pot not the plant). Just don't have the blocker touch the pot (see conduction above).

Silver bubble wrap...
The silver blocks the radiant heat, big help. The fact that it is bubblewrap.... not so much. It does help a little by keeping the reflective material off of the pot reducing conduction. Bubble wrap's strength is in blocking convection (air flow), so it could actually have a negative effect on misters or any other cool air source. But it could help if blowing hot air is an issue. Aluminum foil is the monster blocker of radiant heat. Silver bubble wrap, ya, go for it. A '57 chevy blocks the sun pretty good too.

Combination of strategies is best, but radiant should be the priority to block.

Water the plant as it needs it, don't water to cool it. Obviously if the plant is thirsty, then give it a drink. Don't drown it to cool it.

Will a bigger pot help?
maybe.
It depends on temperature fluctuations. How much for how long. If the burst of heat is high for a short period then a bigger pot can help because of its thermal mass. It slows increase and decreases in temperature change, potentially lowering temps below the level that will damage the plant. If the temp is 70 overnight then 100 at sunrise and stays that way all the way to sunset, then the pot size ain't gonna help (unless you have an Earth sized pot). It will help for a bit at sunrise, but that is it. The amount of temperature fluctuation that can be mitigated is relative to pot size.

At what temps do you get roasted corm? mmmmm, dunno. Ask an expert. I'm sure cultivar has much to do with it.