We operate on NVGs for HEMS/Pol....ITT F4949 goggles with F9800P tubes at 64 line pairs resolution.
We do not advocate goggling or de-goggling other than at a safe height, certainly not at low levels or at hover....definitely from experience not a habit we are comfortable with.
Secondly we have a rule of thumb to deal with reduced vis or very poor contrast conditions....if you are down to 400' and 60kts then abort and turn back seek alternative method (such as IFR).
We use landing light for obstacle detection and augmentation, especially in poor ambient light conditions. IR landing light for covert ops.
If pilot /acft IFR than wx minima can be 3000m and clear of cloud. If night VFR only then wx must be NVMC.
We have found that there is little point over-controlling NVGs, good initial training with follow-up period of supervision and simple set of rules is more than adequate to conduct a safe NVG op.