Lowering the temperature of flat iron?

I need to put some waves/curls/texture in a straight wig and the only thing I have is a flat iron with only one heat setting. I know I can use it to make curls but my only question is if there's a way I can make it so that the temperature is slightly lower. I believe the single heat setting is around 350°F which is below the threshold that my wig can handle (it's an Arda Classic) but they recommend to say in the 300°F range. I don't want to buy another thing to curl it because because I don't want to waste my money.

I also have non heat curlers but i doubt they would work too well because my wig is quite short.