Yes, that is a case of “you don’t put important information in loading screen tips”. Bad Zach, bad!
When the game pulled the same trick again, and revealed that I had blockers all along, a speech balloon with a dumbbell appeared over my head.
Seriously, I tried to think how to change it to bumpers, which are basically pistons with an inverted logic state, it should be a matter of picking a different point for sensors: that design uses two, so I suppose blockers should slightly reduce the block count.
But I couldn’t come up readily with a different location, need to take a little distance from the solution to actually see alternatives.
On that note, I also fiddled a little with it, including a more significant change to how the rockets are welded together: as mentioned, in this design they are welded before assembly, while the variant welded them together and to the shuttle at the same time.
It worked alright, but wasn’t any better than the original in any way. I couldn’t come up with any meaningful enhancement outside of a slightly improved Eviscerator stage that needs a few blocks less.
So, distance. Since it didn’t occurred to me either that platforms weren’t being included in the block count, I went back to tutorial puzzles to reflect on ways to mess with Helio low-block count designs.
Enough times has passed that my solutions are strangers to me, so it’s good practice.