You only need heat up the donor can with hot water from the kitchen faucet. Room temp for the recipient can is cool enough... no need for ice. This way it will take a couple of cycles heating the donor can to top off the recipient can, and you have to check weight with a good scale (accurate to 1g) but that's about it.
It is 100% effective, and worth it to me to spend 83¢ vs $4.95 for a canister of fuel. Indeed, not at all practical on a thru but totally doable for many other trips.