The lower Hokitika River below the highway bridge is fished exclusively with pole nets.
The Taramakau River has far more clear space upstream for set netting on the stony bank. Have you seen this DoC brochure about whitebaiting on the West Coast: http://visitwhanganui.nz/wp-content/uploads/2016/06/Whitebaiting-West-Coast.pdf It has phone numbers for seven Doc offices and information centres on the West Coast. You could ring and ask them about the best place for set netting. Worth a try.