Well, despite all the naysayers and negative nellies, this works very well.
Was at my sisters fixing her turn signal and checked her oil, it was about 1/2 a qt low.
I had stashed a qt of oil and funnel under her hood, but the funnel had disappeared.
So instead of going in search of, I used what I had in hand and I tried this dipstick method. Her fill is below the level of the engine cover, so I know I would have made a mess trying to pour it free hand, and I was able to use the dipstick to pour in 1/2 a qt without spilling a drop, and was able to pour rather quickly.