What I do to promote weight gain and growth is to shove as many reptomin sticks as I can down the mouth of the mouse/rat soon after it thaws.
Another way (sounds gross) is to shove an ice pick into the mouth of the prey item while it is still frozen, then I can get a little more reptomin in the resulting hole.
Once the food is thawed the reptomin will be soft.
With the reptomin stuffed into the prey item, the snake will not even know it's there.
If you are feeding live prey, then get switched over to F/T as soon as you can, and then just stuff the food item.