Nice thought. That I am in no way qualifited to answer.
But if I tried (because of course I will, thank you Dunning, Kruger and all the wise people here), it would be something like:

• Learn how to use a tape measure and trigonometry, and understand Pad X/Y and orthodoxy.
• set up a video camera perpendicular to your bike trainer (because of course you have one), above the bottom bracket and about level with your hips. (By law it must be on the chain side)
• Get a saddle that allows you to rotate your pelvis forwards. If you are unsure what to get, ISM PN 3.0 or 3.1
• set your saddle height, so that your knee angle at the bottom is appropriate. Not overreached, not rocking hips or pointing toes excessively. Too high is bad, too low is not so bad.
• Set your extensions so when you grip the bars your elbows are in the elbow pads, not (a long way) behind them.
• Angle your extensions up somewhat. Not flat, not down.
• Figure out your elbow pad drop from the saddle height based on Slowman's old formula, and set your Pad Y based on that
• Set your Pad X so that your elbows and shoulders are a little over 90 degrees.
• Set your saddle fore-aft so you're sitting comfortably on the correct part of it.
• Review your hip angle at the top of the pedal stroke. If it's too tight, look at shorter cranks.

After that it probably gets more user-specific, but I would guess the following are generally true:

• turtle your head and shrug your shoulders
• use a helmet that sits on your back. If unsure, Gira Advantage 2, Bell Javelin or Giro Aerohead
• Narrow your elbows
• size down your clothing. Wrinkles bad

Then finally

• Post your video to ST and get expert review.

Feel free to pick this apart, I'm not precious

Of course the money-no-object answer is: buy a P5, fly your favourite fitter in your private helicopter to the nearest wind tunnel and go nuts.