I do use mason jars submerged in the water bath and a sous vide unit and I’m doing this with MCT oil.
What I end up doing to avoid a float is to use the appropriate size jar to contents where the contents fill the bulk of the space in the jar. After I put the jars into my pot with the sous vide machine and then slowly fill the pot with water until it just about reaches the “float point” and then turn on the machine and let the magic happen.
So far it’s working great with 1 quart jars with 2c MCT oil : 14g Flower.
I just got a new digital convection oven so I’m gonna oven decarb spot-on accurate before the oil bath for the next batch(s).