nice engineering. i think,sketchup is perfect for this this type engineering. good luck.

Quick check of your model shows about 2871 cubic inches for the desk top alone . Oak density is in the range 37-56 lbs/cubic foot. You can do the math. ust that part of the desk will be very heavy( 60 => ~100 lbs). I am a big fan of torsion panels. They are strong, cheap, and light weight. I would recommend you consider that in your design.