Some time has passed but I didn’t find any better solution than the one described above.
If you do find a better one, or if something has changed with graphics 2.0 [gotta…stop…laughing…] - let us know 
I am facing this issue too. My new game is using spritesheet as much as possible, which suppose to enhance performance, but still get the long black screen. Super annoying, and is enough time for most player to quit the game.
In the other hand, my old game, which is not using spritesheet, has no such issue at all. ( however, apk size is relatively large in old game)
Some time has passed but I didn’t find any better solution than the one described above.
If you do find a better one, or if something has changed with graphics 2.0 [gotta…stop…laughing…] - let us know