At the risk of being totally lambasted for this, I used to find that if I want to get "more sink" without side slpping in the old PA27 Aztec, I slow down, (a lot).
I don't do it very close to the ground, but say from 2000 ft to 700 ft agl, it is an effective way to loose height without too much distance covered, and with a bit of height remaining I could get back to blue line speed quickly if one donk failed.
I have flown the aztec into some very difficult places and sometimes you need every trick in the book to get there.
YOU MUST KNOW YOUR AIRCRAFT VERY WELL BEFORE TRYING THIS. ( I do know the Aztec very well)
I was never comfortable side slipping in a twin.
The Rallye can be held in a full stall giving about 1000 fpm ROD showing nothing on the ASI, but again I would not do this on final approach. (it will turn its self into wind).
Tony