A heat gun is better than a hair dryer; however, you need to use caution and not over-do it. Watch what you are doing closely and those flowers should release and peel off. I took the vinyl wall covering off the walls of my Argosy with a heat gun. Please watch how close you get and how long you leave it in one place. Heat guns are of course hot, but they will probably make this job easier.
They are gone at last! I was right the PO did use some kind of additional yellow looking glue under them.
Ended up combining your ideas about heat and moisture, along with the goof off and a painters tool. We boiled a coffee pot full of water and poured about a cup on each decal - at the same time scraping with the painters tool and they came off. Then a little goof off to get the remaining adhesive.
Thank you all for the help - I didn't think they would ever come off. Photo below - along with the continuing floor project and the installed screen guards purchased from a fellow A/S Fourum member. Odd note on the floor. The plywood is dated 1-66 - stamped "interior use - exterior glue" - the trailer is a 71.