Hello Hakan,
The max loads due to increased righting moment go up in small parts also. The max bending loads in daggerboards and daggerboard trunks go up directly directly with righting moment. Max rudderblade, rudderhead, pintles, gudgens, gudgen bolts and transom increase with righting moment. Max chainplate loads increase as well as chainplate bolts and the hull area immediately around the chainplate.
On a boat like an A class cat that has been through a major weight reduction program, all the fat has been taken out, there is little to no margin for increased loads anywhere. Taking a new/modern A class boat and adding a bigger rig and double trapeze is risky business. The devil is in the details.
Bill
PS If the mast bends too much, raise the hounds, ie 30% if the mainsheet loads are up by 30%. Also add double spreaders below to reduce the max unsupported mast span.