You could do it that way, just make sure you use the full water amount (I know some people who make HP who do use a discount). I also use 1.5-2% sodium lactate (of oil weight) to help keep the soap fluid while I add my FO and colorants so if you have some SL, try adding that to your lye water before adding to the oils. If you've never done it before, it really does help keep it fluid. If you don't have any SL, you can try holding back like 2oz of the water, warming it in the microwave and dissolving roughly 2 teaspoons of sugar per pound of oil, then you can add that to the lye mix before adding to the oils. Sugar is supposed to act like SL and help keep it fluid. You get the plus side of the sugar helping with the bubbly factor.
You are still going to need to work quickly though, so you're going to want to have your FOs premeasured, the scale set up and ready to go (put a piece of plastic wrap over it to help keep the hot soap batter from landing on it). If you are going to use metal bowls/cups to weigh and mix the FO in, I really suggest finding a way to preheat them a bit, because when that soap hits the cold (aka room temp) metal, its going to start to set up and crust on you so you'll likely end up with chunks in the bars. Which isn't a bad thing as long as the soap is done and doesn't zap, just not asthetically pleasing, especially if the FO discolors LOL I would get some of the 1qt HDPE paint mixing containers from Walmart because they're thin enough that they will heat up to the soap's temperature quickly to help keep it warm & more fluid and they are uber easy to scrape clean and wash.