The FHXL might be a pain to build (unless just order the flatpack
) ..... The pensil is quite sufficient for simplification and build economy. Another thing .... Bob Brine's MLTL is highly regarded for the Alpair 10p too and the plans are paypal away ...
plus as discussed, just mail the oval panel
As for the tilting, you may have noticed that most of the finished products are with wooden bases and probably with spikes (plus they use couches that are low) which puts the drivers at proper ear level. In my case my seat is regular height which makes the driver lower and makes the singers image dwarfed. The tilting fixes it and makes the images lifelike.
Sir Joey, when I was driving on my way home that night I realized that the Alpair 10P in FHXL would be perfect for your room!
First, your current speaker placement is a meter or 2 away from the walls (a requirement for FHs) and second; you like tilting the speakers a bit with good results (a natural in FHs design).
Just saying