My question is, would a B-17 have its landing flaps deployed at all at this
lower speed and altitude if it was not landing, just hedge-hopping home?
And
if so, how much?

No.... if I were flying a four engined aircraft with two fans out, the flaps
wouldn't drop out until short final. He's already in serious trouble; any
added
drag might be the straw that breaks the camel's back.

Okay, that's one less thing to think about.

The way I see it now, the base of the diorama will be the coast line of
Belgium, with the Fort just "leaving" Festung Europa with all deliberate speed.

Walt