Why is it so high? The mount is at head hight so placing a bahtinov mask etc when at the zenith is going to be tricky???
Might be using refractors? When building a permanent pier you almost have to make a decision as to whether you're mainly going to be using refractors or reflectors!
My permanent pier is head high. But my 12" Newt is set at waist high at the shortest tripod setting- and that's still too high. If I put the Newt on my obsy pier the business end would be some ten feet off the ground! Now I could have made a shorter obsy pier- but then I would not see over the obsy walls and I like to opperate my cameras at about head high! Lots of things to weigh up when making a pier.....