I wouldn't do that if I were you it really seems like a "gray" to even a "black" hat tactic. It might work for now but in the future, it might create problems that you surely don't want. Mass link building to a certain domain or a chain of domains is not recommended at all.

From my experience, Google does tend to like Wordpress websites. I haven't seen a lot of SquareSpace websites in the top 10 of Google, to be honest, and maybe there's a reason for that. Either way, I'm not telling you to go back to Wordpress but if these are your only two options and your website is suffering... there's not much else you can do.