You only need 1 ounce or so in a shot glass. I keep a steel bowl nested in ice (snow would work) in another bowl. Toss an ounce or two of mash liquid, swirl to cool. Decant onto the shot glass, take the temp, then the pH twice. Record the result.
Takes me about a minute, unless I have recalibrate for some reason.
You can use the later samples with iodine to test for conversion.