This definitely seems like an interesting project! With the enclosure being relatively small compared to the size of the drivers, I’d heavily consider measuring how much volume the magnet takes up (pi*(radius)^2*depth) and subtracting it from your current internal volume so you get a more accurate real internal volume to put into winISD.
Secondly the thinness of fbd cabinet in depth seems really stylish, I like it. Only thing is you leave very little bracing for the front and rear panels so if you go with this, especially with these drivers and that the panels are quite large, I would double up both the front and back panels. Larger panels flex more easily, so bracing or doubling up to increase rigidity is all the more important.
Have you seen to that the excursion of the driver and passive radiator is below their individual Xmax’s. Remember demonstrated SPL is at 1m.
Lastly, depending on what kind of music you like listening to, you might want to consider adding weight to the passive radiator (if possible with this one that is), this will allow you to tune lower. Modern music goes much lower than the 50Hz you usually hear referenced.
Hope some of this helps
