ok I'll say something dumb! strenghten your legs and start gripping the tank. not talking about a full court crushing grip but learn to involve your whole body in riding the bike. learned it from my sports bike buddies.
all things being almost equal, this basicly is a sports bike as far as seating goes. by using the lower body and keeping the arms bent(no straight arms) it takes alot of pressure off the wrist.
took me awhile to get the hang of it but now the thing that gets to me the most is my clutch hand from shifting. almost no sort hands or numbness. just my 2 cents
It's not the riding position as much as the vibe in that specific range.
I've pulled 500 mile days on cafe'd Triumph Thunderbird Sport, Ninjette 250, amongst others.
Been riding 40 years. Tried moving up and back, relocating my grip position etc.
It's to bad the vibes occur at what is normal touring speed around these parts