I have very good experience with Harbeth SHL5 plus, acording to your description, I would suggest you to try polk audio back ported. I have a pair discountinued RTI A1, hang on the wall and right behind a hanged tv, very short space to the left and right, wall to the left and fire place to the right. But they still sound amazing.
This bookshelf comes with a guided port with a hanging hold, and seems polk audiohave some special research and design on the guided port. Chek out their website to see if you can find anyone meet your require
https://www.polkaudio.com/en-ca/category/home-speakers/bookshelf/
And the link below to see their guided port tech