I toured extensively as a 280-lb. rider with a medium load, i.e. two large panniers, and enough bikepacking bags to equal one small pannier. It was through the Baltics and Balkans, as well as one to two week trips to several other countries.

It was on a 2013 Salsa Vaya Travel, on the original DT Swiss 350 hub / X470 rim / 32-spoke wheels, which were rated to only 120kg. I didn't break a spoke or have any other problems with the wheels over thousands of km.

What did happen, eventually (i.e. 6-7 years of riding with and without loads), is that the rims lost their ability to hold true. They suddenly started breaking spokes on relatively tame rides, and becoming out of true within a few rides after getting them serviced.

When I rebuilt them with new rims (DT Swiss HX 491, which are no longer being made), the verdict from my LBS was that rims have come a long way even in the past 10 years, so 36-spoke isn't necessary, even at my size. I wouldn't stress it if I were you - it's all down to hub and spoke choice. Get DT Swiss 350's and go from there.