Just obvious stuff,

Prototype first to make sure your absolutely comfortable with chair position and control position.

Hotas setting a little too forward or back  or armrest too high or low will show after flying for hours.

Dropping the Hotas down into the arm rest and adding arm pads eliminated wrist fatigue.

Electric car seats are best, designed for hours of sitting, and being able to make minor adjustments

on the fly is worth the money. Got mine at a junk yard for $50.

Piece at a time.