YOU BET!!! THOSE COULD ACTUALLY WORK VERY WELL!
For my suit, I found a full set of very lightly used adult size Ice Hockey pads (worth well over $250 new) locally on www.craigslist.org for $25. One of the nice perks of living in a college town. I ended up using almost every piece of it for the base of my AVP suit & it worked out amazingly!
Those pads you found are a great find!