That's such a cool and creative idea! I personally was sometimes confused, because I had placed a card yet there was nothing. Only to realize that the height was way too big for my current position (As far as I understand, the number that is shown when hovering with a card is the height where the structure will spawn, right?) Maybe this could be communicated a bit better to the player. I don't know if it would fit the game but the game could for example disallow placement of structures that the player can't reach because of the height anyways. Or maybe get rid of that structure height mechanic at all?
Anyways, this is a really cool idea that was really well executed.