Different options I could think of:

1) Use nozzle flexiblities to reduce the loads.

2) Send the loads to vendor for approval.

3) Do a WRC 107/297 type analysis to check for local stresses or use FEA to compute local stresses and check if they are within allowable.

4) Pl. note that for fatigue analysis ( Pl+Pb+Q+F) you will have to properly find out the no. of cycles when such excursions will be there and then apply Miner's rule which will give you some comfort margin.

5) Elastic plastic analysis also can be done but depends on your resources, capabilities , time constraint and project/client aggrement.