Yup, anyone find the lake monster yet?
The plane isn't too difficult to spot, theres a map marker somewhere on the lake where a wrecked half submerged boat is, head roughly NW I think. I'll have to confirm that.
Having said that, you may even need the quest 'Volare' for it to be there.
As far as I know, what you've already listed and I believe a high PER is all I can think of. That and increasing the game brightness.
Reno