So many people keep trying to invent a better mousetrap and always fail. Simply removing the drain plugs, probing to insure draining and leaving it dry will never crack anything . With the newer "Quick-Drain" system you can never be sure the connectors in the block are not plugged with rust and scale and do not drain the block. After about 2 years I have found the blocks do not drain because of the rust and debris so simply "draining " by the quick system did not drain the block. So now there will be a freeze crack come springtime .
Same result but not draining everything first before introducing AF with the "thru the drive" system only results in dilution of the AF . How much dilution till it cracks , your call . -10 or +30 . Frozen is frozen.
Does Camco work, Yes. IF YOU DRAIN EVERYTHING FIRST. And draining requires you to remove the quick disconnects at the block drain and probe. Have only discovered 1 manifold that did not drain correctly because of rust and it cracked with some water entering a cylinder thru an open valve. The manifold drain hoses are larger than the block drain hoses.
For the "non-believers" simply remove the hose at the block drain and see what runs out. Its a quick connect so you wont lose that much. If nothing comes out the block drain is plugged .Good luck Springtime.