Flush Verticle Quad Extender

Here’s the question: Is a quad extender FLUSH AND VERTICLE possible?

I’ve come to a conclusion: no. I went through basically every method to make it work and I’m convinced that it’s literally impossible.

I spent a freaking 2 HOURS JUST trying to make the FREAKING LAYOUT.

My first layout attempt worked but only for extension. I found that the retraction is impossible. Why? Because you have to retract the redstone block powering the topmost piston which doesn’t work. Why? 1. I tried retracting it using a piston which everyone decent redstoner knows won’t work because a piston that extends upwards a rs block gets stuck in an updated position. 2. I tried retracting it using slime blocks and that failed because it pulled the floor level down. I switched the floor level to obsidian but that failed because the slime block wouldn’t move passed it.

My second attempt: I got the extension done easily but the retraction also failed. Attempted method of retraction: a piston rising out of floor next to extender was supposed to move the rs block sideways, then the slime blocks could suck the rs block and sideways piston into the floor. Problems with the last method: So many pistons are everywhere and have to do so much to remove the floor allowing slime blocks to go up. There were literally so many other problems that made it impossible.

My better attempt: definitely the second one. I WAS SO GOSH DANG FREAKING CLOSE TO MAKING THE LAYOUT WORK but it just can’t be done.

The question: have you guys made one and or attempted a layout? Please answer!! :D