Drop a u2u to a member called 'flyingbanana'.
I know he has some form of clip-ons on his bike...not sure why he fitted them but perhaps for the same reasons you are mentioning. Could be worth talking too?
I'm afraid what your experiencing is just the nature of the beast. I'm the same 6ft, 15+ stone, and still after a couple of years and numerous set-up changes, find the riding position uncomfortable at times.
May be worth taking some suspension readings at the rear (ride height etc.) and posting what you find.
I run with the rear 'relatively' low, but speed up the steering by running with the steering head on 'steep'. Might be worth considering?
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