I tried these ini tweaks which seems to increase the view distance, but the ocean gets a white line across it which spoils the effect, so I only used the vegetation range increase.

VegetationAdmin.ViewRange=7500.0
Shader.CurrentShaderVersion=3_0
ObjectDetails.fProcessingRangeFadeOutRange_High=60 0.0
ObjectDetails.fRangedBaseLoDOffset_High=600.0
ObjectDetails.fProcessingRangeFadeOutRange_Medium= 1000.0
DistanceHigh.fFarClippingPlane_High=20000.0
DistanceLow.fFarClippingPlaneLowPolyMesh_High=1500 00.0
Render.DOFStart=15000.0
Render.DOFEnd=18000.0
Entity.ROI=6200