It's hard to nail down the precise timeframe the Ewok movies take place in. There was an article in the old fan club newsletter Bantha Tracks referencing a scene (apparently cut) where a young Ewok plays with a carved wooden Imperial Scout Walker. Wicket has learned to speak english (Galactic Standard?) in Battle for Endor, but there have been cop-out explanations to explain away the fact he doesn't speak it in Jedi.
On the other hand, if all the characters introduced in BFE laid low during the Imperial presence, why didn't Wilford Brimely's character try to contact the rebels or go looking for tech he could salvage when there would be tons of wrecked Imperial hardware lying about?
The fan film "The Invisible Enemy" would fit in nicely before Jedi.