So you don't have maps with contours to help assess the altitude of the LS? Or google? Or local knowledge of the terrain? Or an approximate maximum altitude you might be working at?
Just the appropriate graph from the ODM for HOGE on a kneepad coupled with an OAT guage and the altimeter reading would be a pretty good start.
No 'rule of thumb' in flight power check is going to help you assess the wind at a mountain LS - you have to assume no wind assistance and plan accordingly.
PS, I'm not an offshore pilot nor ever wish to be
