Great devlog. I've faced this issue myself in my momentum game, and there's nothing like shared misery among gamedevs. Never considered the open level route, it's a really great solution! Currently I'm looking into the concept of mutators to add a bit more replayability.  You've given me alot to think about for the future though!

OK, Now combine the movement, flashing and breaking properties on a single obstacle.

Of course, I’m kidding. Ad a software developer my self, who more interested in designing software, I would have thought of tackling this issue by procedurally generating the levels, or creating a level which is designed condensed then stretched out. But this only works if you don’t have a story to think of, or don’t want any visuals; still I think these kind of levels can be used for inspiration.

Since you already figured out how you want to tackle this task, I’d rather recommend to stick with it, than to try this. This is just my 0.2 cents. (And I mean worthless idea.)