Hi Mr OFAP,
I have had this problem as well, after a couple of miles hands/fingers tingle and go numb.
At the w/e I was in Halfords(!) and spoke with one of the 'bike' staff about the problem. He rides a road racer type, electric cycle path/gravel type and also a large motorbike.
He had suffered the same problem on all his machines and his cure was taking weight off the hand/wrist by using the core/stomach muscles to help take some of the body 'resting on the hands' weight.
He found this helpfull and to further assist with 'core' strength was doing a number of 'sit ups' daily to increase the time he can ride without the wrist/hand problem.
I can see the logic in what he is doing so will give it a go and see if it helps. I'm just tightening the stomach first and if that helps then I 'may' do a few sit ups to improve things further, my discs permitting!
HTH, I will check in again to see any further tips 'n' tricks for this problem.
Cheers
BootsBoots