Im certainly no kp but Im 80kg and I have lots of tow with a 125ltr hs and big sails.
I find it easy to uphaul an 8.5 np rs and just slightly harder to uphaul a 10.6 rs.
The 10.6 is a load to hold up while slogging in no wind but the board floats it with no problem. Very stable.
Hope this helps.